Cold, becoming Very Mild
Temperatures
The average maximum temperature during December 2022 in Shoreham was 7.5 Celsius (45F), and that was almost 2 Celsius (3.5F) below normal for the time of year. The average minimum temperature was 3.2 Celsius (38F), and that was more than 2 Celsius (3.5F) below average for December. Overall, it was the coldest December in the area for 12 years.
The highest temperature recorded during the month was 13.2 Celsius (56F) on the 13th, but the temperature reached 12.3 Celsius (54F) on the 19th, and there were 10 other days with maxima above 10 Celsius (50F), including 6 days when the temperature was 11 Celsius (52F) or higher.. All of these very mild days occurred after the 18th. After a relatively mild start to the month, with 5 out of the first 6 days having maxima above 7 Celsius (45F), it became much colder. Between the 11th and 16th, day-time temperatures remained below 3 Celsius (37F), although only 2 of these cold days had maxima below 2 Celsius (36F). On the 11th, a high of 0.9 Celsius (34F) occurred, with 1.8 Celsius (35F) recorded on the 15th.
There were several mild nights during December, all of them occurring after the 18th. On 2 nights the temperature stayed above 10 Celsius (50F) . On both the 25th and 31st lows of 10.3 Celsius (50F) were measured, and a further 5 nights had minima above 8 Celsius (46F). The first week of December had minimum temperatures between 2 and 5 Celsius (36-41F), but it then turned much colder. On the 10th and 17th minima of minus 4.3 Celsius (24F) occurred, but the coldest night of the month was the 11th with a low of minus 5.2 Celsius (23F).
The sea temperature decreased from 12 Celsius (54F) at the beginning of the month to around 9 Celsius (48F) at the start of the second week. It then changed little during the remainder of the month.
Frost
There was air frost on 10 nights during December, around 7 nights above average. All of the air frosts occurred between the 8th and 17th. Most of the frosts were moderate with minima between minus 2 and minus 5 Celsius (28-23F), but 4 nights only had a slight frost, and on 2 of those nights, the 12th and 13th, minimum temperatures were above minus 1 Celsius (30F). Grass frost occurred on 12 nights, that was only 2 nights above average. The grass frosts coincided with the air frosts, except for 1 night, the 12th, when a grass low of 0.0 Celsius (32F) occurred. The 18th, 21st and 27th each had grass frost but no air frost. The lowest grass temperature was minus 8.3 Celsius (17F) on the 17th, but lows between minus 5 and minus 6 Celsius (23-21F) occurred on the 9th, 10th, 11th and 18th.
Rain
Rainfall in December amounted to 119.0 millimetres (4.7 ins.), which was only slightly above the monthly average. Measurable rain fell on 16 days, which was 4 days below the average, and wet days (when 1 millimetre (0.04 ins.), or more, of rain falls) numbered 12, which was also 4 days below the average. Apart from showers on the 2nd, which gave 0.8 millimetres (0.03 ins.), the only measurable precipitation during the first 10 days was on the 10th, when 0.4 millimetres (0.02 ins.) of dew were measured. On the afternoon of the 11th there was moderate rain, and it fell with a temperature of minus 2 Celsius (28F). Although only 4 millimetres (0.16 ins. ) of rain were measured, the ice that formed on untreated surfaces was both hazardous and damaging. The ice remained on shaded areas of local pavements and roads until late on the 17th. On the 18th, it rained all day giving a total of 33.2 millimetres (1.3 ins.) and 6.8 millimetres (0.27 ins.) of rain fell on the following day. In fact, there were no completely dry days during the rest of the month, with daily totals including 6.6 millimetres (0.26 ins.) on the 22nd, 10.2 millimetres (0.40 ins.) on the 27th, 13.6 millimetres (0.53 ins.) on the 30th, and 19.8 millimetres (0.8 ins.) on the last day of the year.
Hail
No hail was observed in this part of Shoreham.
Thunder
No thunder was heard in this part of Shoreham.
Snow
A few snowflakes were observed in the freezing rain on the afterrnoon of the 11th, and light snow fell for less than hour in the evening. A very thin layer covered the ground until late afternoon on the following day. Thereafter, a few well-scattered patches remained in shaded spots until late on the 17th. Over, and to the north of, the South Downs, there were 3 to 5 centimetres (1-2 ins.) of snow, and the ground stayed snow-covered for 6 days.
Wind
In the first half of December, winds were mainly light or moderate and blowing from the north or northwest. After the 17th, the winds were persistently from between south and west and generally fresh or strong. At Shoreham Airport, the first gust of the month above 30 knots (34 mph) occurred at midnight on the 19th when south-southwesterlies reached 33 knots (38 mph). The rest of the day was breezy with 38 knots (43 mph) occurring at midday. On the 27th, southwesterly gusts reached 35 knots (40 mph) late in the evening, and on the following afternoon a gust of 40 knots (46 mph) was recorded, also from the southwest. The strong wind continued into the morning of the 29th with 42 knots (48 mph) recorded before dawn. On the morning of the 30th there were strong south-southeasterly winds, these peaking at 41 knots (47 mph). Southwesterly winds returned on the last day of the month, and several gusts reached 32 or 33 knots (37-38 mph).
Fog
Mist thickened into fog at times on the morning of the 1st.
Statistics for December 2022
| Reporting Site | Highest Temp | Lowest Temp | Rain Total (mm) | Wettest | Rain days |
| Shoreham A/P | 13.1 | -6.3 | * | 27 | 22 |
| Thorney Island | 13.5 | -3.1 | * | * | * |
| Gatwick A/P | 13.5 | -8.4 | * | 35 | 17 |
| Herstmonceux | 14.3 | -4.9 | * | 40 | 24 |
| Bournemouth (Hurn) | 14.0 | -8.6 | * | 28 | 18 |
| Middle Wallop | 13.4 | -6.7 | * | 36 | 19 |
| Dieppe | 16.8 | -5.4 | 86 | 27 | 21 |
* Totals unreliable