Shoreham Weather

 

 

Changeable and Rather Wet

 

Temperatures

The average maximum temperature during July 2021 in Shoreham was 22.5 Celsius (69F), and that was about 1 Celsius (<2F) below normal for the time of year. The average minimum temperature was 14.9 Celsius (59F), and that was slightly above the July average.

The highest temperature recorded during the month was 28.0 Celsius (82F), on the 18th, but 7 other days had maxima above 25 Celsius (77F), including the 20th and 22nd, with both days having highs of 26.7 Celsius (80F). All of these warmer days occurred between the 14th and 23rd. On most days (17) maximum temperatures were between 20 and 25 Celsius (68-77F), but there were a few rather cool days. On 6 occasions maxima were below 20 Celsius (68F), including 3 days with highs under 19 Celsius (66F). There were 4 of these cooler days during the first week of July, but the coolest day was the 10th with a maximum of 18.0 Celsius (64F).

There were no especially warm nights during July, but 16 nights had minimum temperatures above 15 Celsius (59F), including 4 nights with minima above 16 Celsius (61F). All of these warmer nights occurred between the 22nd and 26th, with the highest reading occurring on the 22nd when 16.9 Celsius (62F) was recorded. No particularly cool nights occurred during July, although on 3 occasions minima were below 13 Celsius (55F). On 2 of these cooler nights the temperature dipped below 12 Celsius (54F). The coolest night was the 16th with a minimum of 11.5 Celsius (53F).

The sea temperature was 17 Celsius (63F) at first, but soon rose to 18 Celsius (64F), and for the remainder of the month it varied between 18 and 19 Celsius (64-66F),, although it briefly reached 20 Celsius (68F) at the beginning of the fourth week of July.

Frost

No air frost occurred during July The lowest grass temperature occurred on the 11th when 9.4 Celsius (49F) was recorded.   

Rain

Rainfall in July amounted to 64.0 millimetres (2.5 ins.) which was over 30% above the average for the month. Measurable rain fell on 15 days, which was 6 days above the average, and wet days (when 1 millimetre (0.04 ins.) or more of rain falls) numbered 13, and that was 7 days above the average. None of the first 12 days of July were completely dry, although on 4 days there was too little rain to measure, and on most of the other 8 days amounts were small with only 1 day having a total above 4 millimetres (0.15 ins.). That day was the 5th when 19.8 millimetres (0.8 ins.) were recorded. Between the 13th and 22nd no rain occurred, but rain fell late in the evening on the 23rd, and from then until the end of the month there was only 1 completely dry day, and that was the 28th. Amounts of rain were generally small but 4 millimetres (0.15 ins.) were measured on the 23rd, with 15.6 millimetres (0.6 ins.) and 4.8 millimetres (0.2 ins.) falling on the 25th and 26th respectively.

Hail

No hail was observed in this part of Shoreham.

Thunder

There were 4 days when thunder occurred during July. The first storm was heard early in the evening on the 19th. It was quite distant to the northeast and no rain fell. Late in the evening of the 23rd there was thunder and lightning which lasted intermittently into the early hours of the 24th. The last storms of the month occurred on the afternoon of the 31st. Although no rain was recorded in Shoreham, north of the Downs, some torrential bursts were observed, with Steyning measuring over 25 millimetres (1 inch) of rain.

Snow

No sleet or snow was observed this month in Shoreham. 

Wind

July was another ‘westerly’ month with winds blowing from the southwest or northwest, accounting for two-thirds of the daily observations. Southwesterlies were dominant with almost half of the days having winds from that quadrant. Although breezes were often light during the second, third and much of the fourth weeks, a few unusually windy days occurred. At Shoreham Airport, the 6th was a windy day with several gusts from between south and southwest reaching 38 knots (43 mph) both in the morning and afternoon. A northeasterly gust of 33 knots (38 mph) occurred in association with thunderstorms in the early hours of the 24th. The 28th was a windy day with afternoon and evening gusts from the southwest reaching 37 knots (42 mph). However, the windiest day of the month was the 30th. In an unusually destructive windstorm for the time of year, southwesterlies gusted over 40 knots (46 mph) with a peak gust of 43 knots (49 mph) early in the afternoon.    

Fog

There was early fog on the 2nd, and it stayed quite misty with low cloud until the 4th.

Statistics for July 2021

Reporting Site	Highest Temp	Lowest Temp	Rain Total (mm)	Wettest	Rain days
Shoreham A/P	26.1	9.3	44	12	14
Thorney Island	26.8	9.8	92	25	13
Gatwick A/P	30.6	9.3	116	23	15
Herstmonceux	29.1	11.2	83	15	18
Bournemouth (Hurn)	29.6	8.8	107	35	15
Middle Wallop	30.6	10.1	105	30	13
Dieppe	26.2	11.0	68	14	17

Very Dry and Cold

Temperatures

The average maximum temperature during April 2021 in Shoreham was 12.8 Celsius (55F), and that was about 2.5 Celsius (4.5F) below normal for the time of year. The average minimum temperature was 2.9 Celsius (37F), and that was around 4 Celsius (7F) below the April average. Overall, it was the coldest April in the area since 1986, or perhaps 1983. Average minimum temperatures have not been lower in the last 56 years.

The highest temperature recorded during the month was 17.6 Celsius (64F), on the 24th, although the 23rd was not far behind with 17.3 Celsius (63F). Only 3 other days had maxima above 15 Celsius (59F0, and the 1st, with a high of 15.7 Celsius (60F), was the only one of these milder days to occur before the 20th. On most days (18) maxima were between 10 and 14 Celsius (50-57F), but several cold days occurred during the early part of the month. On 4 days the temperature failed to reach 10 Celsius (50F), with all of these cold days falling between the 5th and 10th. On the 10th a high of 8.0 Celsius (46F) was recorded, but the coldest day was the 7th with a maximum temperature of just 7.5 Celsius (45F).

Anticyclonic weather, the mean sea level pressure was some 8 millibars above average, led to many calm and clear nights. As a result, there were very few mild nights. The first night of the month had a low of 10.3 Celsius (50F), but thereafter, the 24th, with a low of 7.2 Celsius (45F) was the only other night with a minimum above 6 Celsius (43F). A further 3 nights had lows between 5 and 6 Celsius (41-43F), but the majority of nights (21) recorded minima between 0 and 5 Celsius (32-41F). Colder nights did occur, and on both the 7th and 13th minimum temperatures of minus 1.8 Celsius (29F) were measured.

The sea temperature was around 9 Celsius (48F) during most of April, but struggled closer to 10 Celsius (50F) towards the end of the month.

Frost

Air frost occurred on 3 nights during April, and that was a couple of nights above average for the time of year. However, there were 19 grass frosts, and that was a remarkable 15 more than can be expected in a normal April. The 7th, 12th and 13th each had air frosts, but the air temperature fell to between 0 and 1 Celsius (32-34F) on 6 nights, and these nights had fairly low grass temperatures. Although no grass frosts occurred on the first 5 nights of April, only the 10th and 21st were completely frost-free between the 6th and 23rd. Grass frost was also observed on 3 out of the last 4 nights of the month. On many nights (10) the grass frost was slight with minimum readings between 0 and minus 2 Celsius (32-28F), but particularly early in the month, grass temperatures were much lower. On 3 nights, the 7th, 12th and 13th, grass minima were below minus 5 Celsius (23F), with the lowest value of minus 6.7 Celsius (20F) occurring on the 13th.   

Rain

Rainfall in April amounted to just 2.3 millimetres (0.1 ins.). This was about 7% of the monthly average. Measurable rain fell on 3 days, which is 6 days below average, and wet days (when 1 millimetre (0.04 ins.) or more of rain falls) numbered 1 day, and that was 5 days below average. Although it was only the driest April in the area since 2007, it ranked in the top 5 dry Aprils in 140 years of local records. Almost uniquely, the first day of April was, like the first day of March, cloudless. A little precipitation occurred on 3 out of the first 9 days of the month, but not enough to dampen the ground. On the 10th the rain was just measurable (0.1 millimetres (less than 0.01 ins.) but only measurements of 0.2 millimetres (0.01 ins.) are considered to be significant. On the following day, the 11th, afternoon showers, followed by overnight precipitation gave 0.8 millimetres (0.03 ins.) with 0.2 millimetres (0.01 ins.) on the following day. No more measurable rain fell until the 28th, when light rain during the day produced 1.2 millimetres (0.05 ins.). Light showers occurred on the 30th, but failed to add anything to the monthly total.

Hail

No hail was observed in this part of Shoreham.

Thunder

No thunder was heard in this part of Shoreham.

Snow

Light sleet and snow showers occurred early and late in the afternoon on the 6th, and sleet, with a little wet snow, was observed on the morning of the 12th. 

Wind

With high pressure dominating, winds were often light, especially at night, and directions were variable, although northeasterly breezes accounted for almost a third of the observed directions, and several mornings had northwesterly winds blowing down the Adur valley. At Shoreham Airport, the weather station was not operational between the 9th and 19th, but during the remainder of the month there were no gusts of 30 knots (34 mph) or more reported.    

Fog

Patchy sea fog occurred for a while in the afternoon on the 20th,

Statistics for April 2021

Reporting Site	Highest Temp	Lowest Temp	Rain Total (mm)	Wettest	Rain days
Shoreham A/P	16.7	-2.7	*	*	*
Thorney Island	16.1	-3.0	1.4	0.6	3
Gatwick A/P	17.5	-4.9	7	2	4
Herstmonceux	16.3	-3.5	5	3	6
Bournemouth (Hurn)	17.3	-5.2	9	4	5
Middle Wallop	17.8	-2.6	19	13	4
Dieppe	17.8	-2.2	19	15	5

* Data missing

Dry and Anticyclonic

Temperatures

The average maximum temperature during March 2021 in Shoreham was 11.6 Celsius (53F), and that was about 1 Celsius (<2F) above normal for the time of year. The average minimum temperature was 4.2 Celsius (40F), and that was around 0.5 Celsius (<1F) below the March normal.

The highest temperature recorded during the month was 19.6 Celsius (67F), on the 30th, and on the 31st a maximum of 18.5 Celsius (65F) occurred. However, the only other day with a temperature above 15 Celsius (59F) was on the 16th, when 15.1 Celsius (59F) was measured. On most days, the temperature rose to between 10 and 15 Celsius (50-59F) but there were a few cool days, mainly during the first week of March. On 7 occasions the temperature failed to reach 10 Celsius (50F), but the only cool day after mid-month was the 18th with a high of 9.8 Celsius (50F). A cluster of cool days occurred between the 4th and the 8th, and although the 5th and 7th both had maxima below 8 Celsius (46F), the 4th, with a maximum of 6.4 Celsius (44F), was the only day when the temperature was under 7 Celsius (45F).

No particularly mild nights occurred during March, but the temperature only fell to 9.0 Celsius (48F) on the 11th, and there were minima of 8.7 Celsius (48F) on the 26th and 8.6 Celsius (47F) on both the 28th and 29th. However, there were only 4 other nights when the temperature stayed above 6 Celsius (43F). On many nights (11), the minima were between 2 and 4 Celsius (36-39F), but some colder nights occurred. On the 7th a low of minus 0.6 Celsius (31F) occurred, with minus 2.6 Celsius (27F) was measured. After the 9th, the only temperature below 2 Celsius (36F) was the low of 0.3 Celsius (32F) recorded on the 20th.

The sea temperature was around 7 Celsius (45F) at the beginning of March, before slowly rising to 8 Celsius (46F), and then to 9 Celsius (48F) on the last 2 days of the month.

Frost

Air frost occurred on 2 nights during March, and that was average for the time of year. However, there were 17 grass frosts, and that was 8 more than can be expected in a normal March. No prolonged period was free of grass frost during March, with 3 consecutive days, beginning on the 3rd, the longest spell. On each night between the 6th and 10th, and again between the 22nd and 25th, grass frost occurred, but on many nights throughout the month, frost was slight. On 7 nights the grass temperature dipped below minus 3 Celsius (27F), but the only night with a minimum below minus 5 Celsius (23F) was on the 8th when minus 7.2 Celsius (19F) was measured.   

Rain

Rainfall in March amounted to 30.6 millimetres (1.2 ins.). This was about 50% of the monthly average. Rain fell on 10 days, which is 8 days below average, and wet days (when 1 millimetre (0.04 ins.) or more of rain falls) numbered 6 days, and that was 6 days below average. The month began cloudless, but rain on the 3rd amounted to 3.4 millimetres (0.13 ins.). No measurable rain fell between the 4th and the 9th, but during an unsettled spell that lasted around a week, the bulk of the month’s rain fell. On the 10th, a total of 9 millimetres (0.35 ins.) was measured, and the 12th, with 11.2 millimetres (0.44 ins.), was the wettest day of the month. After the 11th, rain was sporadic and mostly light. The largest amount was 2 millimetres (0.08 ins.) on the 25th, and between the 13th and the end of the month (19 days) less than 7 millimetres (0.25 ins.) of rain fell.

Hail

Small hail briefly fell in heavy showers late in the afternoon and early in the evening on the 12th.

Thunder

No thunder was heard in this part of Shoreham.

Snow

No sleet or snow fell in this part of Shoreham. 

Wind

Although the mean sea level pressure readings were much higher than average (around 11 millibars on the barometer), the winds were often quite strong, especially during the second and last weeks of March. There was no dominant direction, with the daily readings equally divided between southwest and northeast, with several days having winds from the northwest. At Shoreham Airport, southwesterly gusts reached 35 knots (40 mph) on the evening of the 10th, and squally southwesterly gusts peaked at 45 knots (51 mph) in the early hours of the 11th. The strong southwest winds continued through the rest of the day, and into the 12th and 13th. A gust of 33 knots (38 mph) occurred on the afternoon of the 12th, with 42 knots (48 mph) recorded on the morning of the 13th. Lighter winds then prevailed until the 26th when a southwesterly gust of 32 knots (36 mph) was registered. Although breezy on the 28th, no further gusts above 30 knots (32 mph) were reported during March.    

Fog

Both the 2nd and 3rd were very misty at times, but no fog was reported at the time of the morning observation (0900 UTC).

Statistics for March 2021

Reporting Site	Highest Temp	Lowest Temp	Rain Total (mm)	Wettest	Rain days
Shoreham A/P	16.6	-3.9	21	6	13
Thorney Island	17.4	-4.2	21	13	10
Gatwick A/P	23.0	-5.3	39	10	14
Herstmonceux	20.8	-3.4	36	8	14
Bournemouth (Hurn)	20.2	-5.0	35	10	14
Middle Wallop	21.8	-1.2	39	9	13
Dieppe	23.8	-0.5	31	5	16

A Month of Contrasts

Temperatures

The average maximum temperature during February 2021 in Shoreham was 8.0 Celsius (46F), and that was about 0.5 Celsius (<1F) below normal for the time of year. The average minimum temperature was 4.1 Celsius (39F), and that was around 0.5 Celsius (<1F) above the February normal.

The highest temperature recorded during the month was 12.9 Celsius (55F), on the 27th, but the maximum on the 21st was 12.7 Celsius (55F), and 2 other days had highs above 12 Celsius (54F). On a further 9 days the temperature exceeded 10 Celsius (50F). Apart from the 2nd and 5th, all of these milder days occurred after the 17th. There was a brief cold spell during the second week. In fact, apart from the 1st, when a high of 4.9 Celsius (41F) was recorded, there were only 7 other days with maxima below 5 Celsius (41F). Each of these days had highs of 3 Celsius (37F) or lower. The temperature only reached minus 0.8 Celsius (30F) on the 8th, with 0.4 Celsius (32F) recorded on the 9th.

No especially mild nights occurred during February, but the temperature only fell to 10.1 Celsius (50F) on the 24th, and there were 5 other nights with minima above 8 Celsius (46F), including a low of 9.8 Celsius (50F) on the 20th. The only one of these milder nights occurring before the 18th, was on the 3rd, when a minimum of 8.1 Celsius (46F) was measured. The coldest nights were clustered between the 7th and 14th when each of these nights had minima below 3 Celsius (37F). On 5 other occasions, the temperature fell to between 2 and 3 Celsius (36-37F), including each of the last 3 nights of the month. The lowest temperature was minus 2.6 Celsius on the 11th, but minus 2.3 Celsius was recorded on the 13th.

The sea temperature was around 7 Celsius (45F) at the beginning and end of February, but dropped to 6 Celsius (43F) for a while during, and after, the cold weather.

Frost

Air frost occurred on 6 nights during February, and that was 1 day above average for the time of year. All the air frosts occurred between the 8th and 13th, and although numerically they were mostly slight, combined with brisk east winds, they proved to be damaging to the more tender plants and shrubs. There were 13 nights with grass frosts, which is 1 below the average. The grass frosts occurred in 2 batches. These were from the 4th to the 14th, with 9 frosts, and from the 23rd to the 28th, when 4 grass frosts were recorded. Grass temperatures were not particularly low, with the lowest values being minus 6.7 Celsius (20F) on the 11th and minus 4.4 Celsius (24F), on the 13th.   

Rain

Rainfall in February amounted to 55.8 millimetres (2.2 ins.). This was less than 10% below average for the month. Rain fell on 13 days, which is 5 days below average, and wet days (when 1 millimetre (0.04 ins.) or more of rain falls) numbered 11 days, and that was 1 day below average. The month began wet with 6 millimetres (0.25 ins.) of rain falling overnight on the 1st, with a further 9 millimetres (0.35 ins.) on the 2nd. In fact, measurable precipitation was recorded on each of the first 7 days of February, including a fall of 7 millimetres (0.3 ins.) on the 4th. The next measurable rain fell on the 14th, and it was the wettest day of the month with 11.6 millimetres (0.45 ins.) recorded. A further 6.8 millimetres (0.3 ins.) were added to the total on the 16th, but the second half of February was considerably drier than the first half. Between the 17th and the end of the month, there were only 2.6 millimetres (0.1 ins.) of rain.

Hail

No hail was observed in this part of Shoreham.

Thunder

No thunder was heard in this part of Shoreham.

Snow

Sleet or snow fell on 4 days during February. Light snow or snow grains fell from late morning until late afternoon on the 7th, and on the 8th light snow or snow grains fell throughout the day. A little snow fell on the morning of the 9th, and light snow showers occurred on the 10th. Lying snow (grassy surfaces more than half covered) was recorded on 2 mornings, the 8th and 9th, but it amounted to little more than a dusting, although a few patches remained until the evening of the 12th. 

Wind

Southeasterly winds were dominant during February, accounting for nearly half of the daily observations. Just over a quarter of the days had southwesterly winds, with a similar proportion having winds from the northeast. On many days the wind was gentle or moderate, but during the cold spell, the easterlies were occasionally fresh. At Shoreham Airport, southwesterly gusts reached 32 knots (36 mph) on the evening of the 2nd, and northeasterlies gusted to 36 knots (41 mph) on the evening of the 7th with the temperature just below 0 Celsius (32F). The temperature was also below zero when northeasterly winds gusted to 32 knots (36 mph) on the afternoon of the 9th, but during the rest of the month there were no further gusts above 30 knots (34 mph).    

Fog

There was 1 day with fog at the time of the morning observation (0900 UTC), and that was on the 6th. However, there was early fog on the 5th, and the 22nd was foggy for a while in the afternoon. Also, the morning of the 28th was very misty over the hills (viewed from Shoreham Airport).

Statistics for February 2021

Reporting Site	Highest Temp	Lowest Temp	Rain Total (mm)	Wettest	Rain days
Shoreham A/P	12.3	-4.3	48	10	16
Thorney Island	12.0	-4.4	56	8	19
Gatwick A/P	14.5	-5.3	53	11	17
Herstmonceux	14.2	-4.2	57	14	15
Bournemouth (Hurn)	13.7	-4.7	76	18	20
Middle Wallop	14.0	-3.8	58	10	27
Dieppe	18.9	-5.3	26	5	15

Cold and Very Wet

Temperatures

The average maximum temperature during January 2021 in Shoreham was 6.8 Celsius (44F), and that was almost 2 Celsius (>3F) below normal for the time of year. The average minimum temperature was 2.4 Celsius (36F), and that was also nearly 2 Celsius (>3F) below the January normal.

The highest temperature recorded during the month was 11.8 Celsius (53F), on the 29th, but the previous day had a high of 11.3 Celsius (52F). On 2 other days, the 13th and 14th, temperatures rose above 10 Celsius (50F). On most days (19) the temperature rose to between 5 and 10 Celsius (41-50F), although 7 of these days had highs between 5 and 6 Celsius (41-43F). On 5 occasions the temperature failed to rise above 3 Celsius (37F), with all of these lower values occurring within the first 10 days of the month. There were 4 consecutive cold days beginning on the 7th, but the only day with a temperature below 2 Celsius (36F) was the 10th, when a high of 0.9 Celsius (34F) was recorded.

No especially mild nights occurred during January. In fact, only 9 nights had minimum temperatures above 5 Celsius (41F). The mildest night was the 20th, with a low of 9.2 Celsius (49F), but a further 4 nights had minima above 8 Celsius (46F). The coldest nights were early in the month and during the fourth week. On each of the first 11 nights of January the temperature fell below 3 Celsius (37F) and 5 consecutive nights, beginning on the 22nd, had minima below 0 Celsius (32F). The lowest temperature was minus 3.4 Celsius (26F) on the 8th, but minus 2.9 Celsius (27F) was recorded on the 10th, and minus 2.7 Celsius (27F) occurred on the 24th.

The sea temperature was around 8 or 9 Celsius (46-48F) at the beginning of January, but for much of the month it was nearer to 7 or 8 Celsius (45-46F).

Frost

Air frost occurred on 11 nights during January, and that was 8 days above average for the time of year. Most of the frosts were slight and occurred in 2 spells. The 7th to the 10th, and the 22nd to the 26th inclusive. The exceptions were on the 1st and 18th, when slight frosts gave minimum temperatures of minus 0.1 Celsius (32F) and minus 0.8 Celsius (31F) respectively. There were 13 nights with grass frosts, which is 1 above the average. The lowest grass minimum temperature was minus 7.8 Celsius (18F) on the 24th, but minus 7.2 Celsius (19F) occurred on the 26th, and on a further 3 nights the grass temperature fell to minus 5 Celsius (23F) or lower.   

Rain

Rainfall in January amounted to 102.4 millimetres (4 ins.). This was more than double the monthly average. Rain fell on 24 days, which is 6 days above average, and wet days (when 1 millimetre (0.04 ins.) or more of rain falls) numbered 19 days, and that was 7 days above average. Precipitation was measured on the first 7 days of the month, but most of it was light, with the highest daily total only 3.2 millimetres (0.1 ins), this occurring on the 5th. In fact, the reading of 0.4 millimetres (0.02 ins.) on the 7th was entirely made up of melted frost and dew. The 8th, 9th and 10th were all completely dry days, with only 2 other completely dry days observed during the rest of January. Daily totals of 5 millimetres (0.2 ins) or more were measured on the 14th, 15th and 16th, and after a dry day on the 17th, a further 2 consecutive days received more than 5 millimetres (0.2 ins.) of rain. The last completely dry day occurred on the 25th, and this was followed by some of the heaviest rain of the month. The last 6 days of January had over 43 millimetres (1.7 ins.) of rain, including daily totals of 14.8 millimetres (0.6 ins.) on the 27th and 11.6 millimetres (0.45 ins.) on the 28th.

Hail

No hail was observed in this part of Shoreham.

Thunder

No thunder was heard in this part of Shoreham.

Snow

A little sleet fell in a shower around dawn on the 6th. Sleet was observed briefly late morning on the 24th and light snow fell late evening on the same day, although it failed to settle. 

Wind

Winds were predominantly from the north or northwest during January, accounting for just over half the monthly total. The remaining days were fairly evenly divided between northeast and southwest winds. During the first half of the month, gentle or moderate breezes blew, but in the second half of January, the wind was often fresh or strong. At Shoreham Airport, a southerly gust of 30 knots (34 mph) occurred on the morning of the 16th, the first significant gust of the month. The 19th, 20th and early part of the 21st were windy, with southwesterly gusts of 35 knots (40 mph) in the early hours of the 19th, a gust of 38 knots (43 mph) on the evening of the 20th, and 46 knots (53 mph) around midnight on the 21st. Southwesterly winds again on the 29th gusted to 37 knots (42 mph) in the late morning, but on the 30th winds became northeasterly and a gust of 31 knots (35 mph) was measured in the late morning.    

Fog

There were 4 days when fog was observed at the mid morning observation. On the 9th there was mist, fog and low cloud in the morning, with fog returning in the evening. Dense freezing fog occurred on the morning of the 10th, and fog formed for a while after overnight rain on the 13th. Lastly, sea fog formed between rain bands on the morning of the 28th.

Statistics for January 2021

Reporting Station	Highest Temp	Lowest Temp	Rain Total (mm)	Wettest	Rain days
Shoreham A/P	12.0	-5.2	78	14	23
Thorney Island	12.2	-4.1	70	12	20
Gatwick A/P	13.4	-4.8	106	17	22
Herstmonceux	12.4	-4.7	99	17	22
Bournemouth (Hurn)	13.3	-5.2	98	19	20
Middle Wallop	13.3	-2.9	90	19	20
Dieppe	13.2	-3.4	101	13	23

Wet and Rather Cold

Temperatures

The average maximum temperature during December 2020 in Shoreham was 8.4 Celsius (47F), and that was about 1 Celsius (1.8F) below normal for the time of year. The average minimum temperature was 4.8 Celsius (41F), and that was around 0.5 Celsius (<1F) below the December normal.

The highest temperature recorded during the month was 12.4 Celsius (54F), on the 23rd, but there were 2 other days with highs above 12 Celsius (54F); both the 14th and 21st had maxima of 12.2 Celsius (54F). There were a further 8 days with maxima between 11 and 12 Celsius (52-54F) and another 2 days with highs above 10 Celsius (50F). All of these milder days occurred between the 11th and 26th. December had several cold days, and maximum temperatures were below 5 Celsius (41F) on 6 occasions. The 7th and 8th had highs of 4.2 Celsius (40F) and 3.5 Celsius (38F) respectively, but the other 4 cold days all occurred during the last week of December. On 2 of these cold days the high was below 4 Celsius (39F). The 29th had a high of 3.7 Celsius (39F), but the last day of the month was the coldest with a maximum temperature of 1.1 Celsius (34F). It was also the coldest day of the year.

A few mild nights occurred during December, and on 4 occasions the minimum temperature was above 10 Celsius (50F). The mildest night was the 22nd with a low of 11.3 Celsius (52F), but the preceding night was only a little less mild with a minimum of 11.1 Celsius (52F). All of the milder nights occurred between the 18th and 22nd. The coldest nights were generally at either end of the month. On 12 nights the minimum temperature was below 3 Celsius (37F), with 5 of these cold nights occurring between the 2nd and 9th, and another 6 nights between the 25th and the end of the month. Although lows of 0.1 Celsius (32F) and 0.5 Celsius (33F) occurred on the 7th and 10th respectively, the lowest values were in the last week of the month. On the 30th, a minimum temperature of minus 1.2 Celsius (30F) was recorded.

The sea temperature was around 11 or 12 Celsius (52-54F) at the beginning of December but fell to 9 or 10 Celsius (48-50F) by the end of the first week, and to 8 or 9 Celsius (46-48F) during the last week of December.

Frost

Air frost occurred on 3 nights during December, and that is average for the time of year. All frosts were slight, with minima of minus 0.2 Celsius (32F), minus 1.2 Celsius (30F) and minus 0.9 Celsius (30F) occurring on the 26th, 30th and 31st respectively. There were 12 grass frosts in December, and that’s 1 above average. With the exception of both the 9th and 14th, when grass minima of minus 2.5 Celsius (27F) and minus 2.8 Celsius (27F) occurred, the grass frosts occurred in the first and last weeks of the month. On both the 26th and 28th the grass minimum temperature was minus 3.9 Celsius (25F), but on the 30th the temperature dipped to minus 5 Celsius (23F).   

Rain

Rainfall in December amounted to 174.6 millimetres (6.9 ins.). This was almost 90% above the monthly average, and appears to be one of the wettest Decembers in the area for nearly 90 years. Rain fell on 23 days, which is 3 days above average, and wet days (when 1 millimetre (0.04 ins.) or more of rain falls) numbered 20 days, and that was 5 days above average. The first day of the month was dry, but on the 2nd, rain in the afternoon and overnight amounted to 6 millimetres (0.25 ins.) and on the 3rd the total was 25.4 millimetres (1 inch). On the 5th another 5.2 millimetres (0.2 ins.) were added to the total, with 12 millimetres (0.5 ins.) falling on the 9th. Daily totals over 5 millimetres (0.2 ins.) occurred on the 11th, 13th, 18th and 19th, with 11 millimetres (0.4 ins.) measured on the 20th, nearly 10 millimetres (0.4 ins.) on the 21st, and 10.2 millimetres (0.4 ins.) on the 22nd. Less rain fell on the 23rd, a mere 8 millimetres (0.3 ins.) Between the 2nd and 23rd there were only 2 completely dry days, the 9th and 15th. The 24th and 25th were both dry, but 25.4 millimetres (1 inch) of rain fell on the 26th, with 20.6 millimetres (0.8 ins.) falling on the 28th. The last 3 days of the month were dry.

Hail

Soft hail fell during an early afternoon shower on the 5th, and small hail was observed for a couple of minutes during the evening of the 19th.

Thunder

No thunder was heard in this part of Shoreham.

Snow

No sleet or snow was observed in this part of Shoreham. 

Wind

December was mostly a cyclonic month with mean sea level pressure some 9 millibars below average. The main areas of low pressure were generally over, or to the north of, Britain with winds blowing from a westerly point on 22 days, these equally divided between northwest and southwest. It was frequently windy, especially towards the end of the month. At Shoreham Airport, southwesterly gusts reached 37 knots (42 mph) on the afternoon of the 3rd, and 30 knots (34 mph) on the afternoon of the 13th, in the early hours of the 14th, and once again early during the evening on the 16th. Winds were quite squally on the 19th, and an isolated gust in the afternoon reached 35 knots (40 mph), with a gust of 33 knots (38 mph) occurring early on the 20th. The evening of the 26th became very windy, with the strong winds lasting until around dawn on the 27th. Southwesterly gusts reached 47 knots (54 mph) at midnight, and 54 knots (62 mph) just before dawn. These were the last significant gusts of the month.    

Fog

There was fog on the evening of the 6th, this lasting until after mid morning on the 7th. Further patchy fog occurred through much of the morning on the 8th.

Statistics for December 2020

Reporting Station	Highest Temp	Lowest Temp	Rain Total (mm)	Wettest	Rain days
Shoreham A/P	13.3	-2.2	123	20	23
Thorney Island	12.5	-2.5	129	23	25
Gatwick A/P	13.0	-2.8	125	24	23
Herstmonceux	13.5	-2.0	176	36	24
Bournemouth (Hurn)	13.6	-3.7	157	34	23
Middle Wallop	13.4	-3.7	113	17	22
Dieppe	14.8	-1.6	67	12	22

Very mild and Changeable

Temperatures

The average maximum temperature during November 2020 in Shoreham was 12.7 Celsius (55F), and that was about 1.5 Celsius (<3F) above normal for the time of year. The average minimum temperature was 8.8 Celsius (48F), and that was almost 3 Celsius (4.5F) above the November normal. Overall, it was the mildest November in Shoreham for 9 years.

The highest temperature recorded during the month was 16.1 Celsius (61F) on the 1st, but there were 3 other days when the temperature rose above 15 Celsius (59F), the 2nd, 8th and 9th; with a further 5 days having maxima above 14 Celsius (57F). All of these milder days occurred during the first 18 days of the month. Only 4 days during November had maximum temperatures below 10 Celsius (50F), with 3 of these cooler days occurring during the last 5 days of the month. On the 26th a high of 8.0 Celsius (46F) was recorded, but the coolest day was the 5th when the temperature only reached 7.6 Celsius (46F).

Many mild nights occurred during November, and on 15 nights the temperature stayed above 10 Celsius (50F). The mildest night was the 2nd when a low of 14.8 Celsius (59F) was recorded. This appears to have been the mildest November night in Shoreham for more than 55 years. No other nights had minimum temperatures above 13 Celsius (55F), but on 5 nights the temperature remained at 12.0 Celsius (54F) or higher. The last of these mildest nights occurred on the 17th when 12.0 Celsius (54F) was recorded. For a late autumn month, the number of cold nights was unusually low. Minimum temperatures below 5 Celsius (41F) were recorded on only 4 occasions, with just 3 of these nights having lows under 4 Celsius (39F). On the 4th and 5th minima of 2.4 Celsius (36F) and 1.6 Celsius (35F) respectively occurred, but the coldest night was the 20th when 0.9 Celsius (34F) was measured.

The sea temperature was around 13 or 14 Celsius (55-57F) at the beginning of November, falling slowly to 11 or 12 Celsius (52-54F) by the end of the month.

Frost

No air frost occurred during November, but there were 3 grass frosts. The 4th and 5th both had slight grass frosts, but the lowest temperature on the ground occurred on the 20th with a low of minus 2.2 Celsius (28F).   

Rain

Rainfall in November amounted to 66.6 millimetres (2.6 ins.). This was around 10% below the monthly average. Rain fell on 18 days, which is 1 day above average, but wet days (when 1 millimetre (0.04 ins.) or more of rain falls) numbered only 9 days, and that was 4 days below average. The month began with outbreaks of rain and drizzle, and a total for the day of 4.2 millimetres (0.17 ins.). A little rain occurred on the 2nd, but no measurable rain fell on the following 5 days. Light rain and drizzle occurred on the 8th, but showers, or longer spells of rain, gave 8.6 millimetres (0.34 ins.). The weather remained unsettled, and a further 6.6 millimetres (0.26 ins.) occurred on the 11th. Rain fell for much of the day on the 14th, but torrential rain overnight led to a total of 29.8 millimetres (1.17 ins.) for the rainfall day (0900-0900 UTC). Another 6 millimetres (0.24 ins.) fell on the 15th, but then pressure built and rainfall totals became much lower. Between the 16th and the end of the month, only 7.2 millimetres (0.3 ins.) of rain fell, with the highest daily total of 3.4 millimetres (0.13 ins.) falling on the 20th. Even though the rainfall total for the second half of November was low, there were only 4 completely dry days.

Hail

Small hail fell in showers on the afternoon of the 15th.

Thunder

Thunder occurred early and late in the afternoon on the 15th, but in total there were only 3 rumbles.

Snow

No sleet or snow fell during November. 

Wind

Less southwesterly winds than usual occurred during November, with these accounting for less than a third of daily observations. Northwesterly winds had a similar share, with southeasterly breezes also occurring on several days. Pressure was well above average during the second and fourth weeks of the month and winds were generally light, but during the remainder of November it was more cyclonic and occasionally stormy. At Shoreham Airport, the beginning of the month was windy with southwesterly gusts reaching 36 knots (41 mph) on the morning of the 1st, 38 knots (43 mph) in the early hours of the 2nd, and 44 knots (50 mph) around dawn on the 3rd. The evening of the 11th was windy with southerly gusts reaching 35 knots (40 mph). South to southwesterly winds were strong through much of the 14th and 15th. Gusts reached 34 knots (39 mph) on the evening of the 14th and 47 knots (54 mph) on the afternoon of the 15th. Southwesterly gusts reached 31 knots (35 mph) overnight on the 19th with no further gusts above 30 knots (34 mph) during the rest of the month.    

Fog

There was fog for much of the day on the 5th, but it was thickest towards the river with this part of Shoreham having the sun shining through the fog. There was also fog for a while overnight on the 11th.

Statistics for November 2020

Reporting Station	Highest Temp	Lowest Temp	Rain Total (mm)	Wettest	Rain days
Shoreham A/P	16.3	-0.6	52	30	22
Thorney Island	16.3	0.2	72	34	20
Gatwick A/P	16.5	-2.0	69	30	21
Herstmonceux	16.7	0.2	76	36	25
Bournemouth (Hurn)	16.4	-2.1	64	21	22
Middle Wallop	16.5	-0.7	67	21	22
Dieppe	19.0	0.0	39	11	11