Mild and Very Wet, then Dry and Rather Cold
Temperatures
The average maximum temperature during January 2023 in Shoreham was 8.7 Celsius (48F), and that was almost 0.5 Celsius (1F) above normal for the time of year. The average minimum temperature was 3.8 Celsius (39F), and that was around 0.2 Celsius (<0.5F) above average for January.
The highest temperature recorded during the month was 12.1 Celsius (54F) on the 4th, but the temperature reached, or exceeded, 11.0 Celsius (52F) on 11 further occasions, including 11.7 Celsius (53F) on both the 10th and 14th. The maximum reached 11.6 Celsius (53F) on both the 1st and 5th, a value shared with the 31st. However, the maximum on the 31st was the only high above 10 Celsius (50F) between the 15th and the end of the month. Whereas, between the 1st and 14th, there were only 2 days with maxima below 10 Celsius (50F). The coolest of these was the 9th with a high of 9.4 Celsius (49F). The cold weather arrived quickly after mid-month. A high of 5.6 Celsius (42F) on the 16th was followed by a maximum of 1.4 Celsius (34F) on the 17th. The temperature then stayed below 7 Celsius (45F) until the 26th and included highs of 4.4 Celsius (40F) on the 23rd, and values between 5.0 and 5.3 Celsius (41F) on the 18th, 19th, 24th and 25th.
There were several mild nights during January, with all of them, bar 1, occurring before the 14th. On 4 nights the temperature stayed above 10 Celsius (50F) . The minimum was 11.2 Celsius (52F) on the 4th, the mildest night of the month, but 10.6 Celsius (51F) was recorded on the 1st, and 10.3 Celsius (50F) occurred on both the 7th and 12th. A further 5 nights had minima above 7 Celsius (45F), but only 1 of these milder nights occurred after the 13th. That night was the 30th when 7.1 Celsius (45F) was recorded. Almost all the cold nights were during the second half of January. A minimum of 2.7 Celsius (37F) was measured on the 10th, but this was the only cold night before the 16th. From the 16th until the end of the month there were 12 nights with lows under 3 Celsius (37F). It was particularly cold at night from the 17th to the 23rd with minima of minus 3.5 Celsius (26F), minus 4.3 Celsius (24F) and minus 3.2 Celsius (27F) on the 17th, 18th and 23rd respectively.
The sea temperature was around 9 Celsius (48F) until mid month, then 7 or 8 Celsius (45-46F).
Frost
There was air frost on 7 nights during January, around 2 nights above average. All of the air frosts occurred between the 17th and 23rd and they were slight or moderate with night temperatures ranging from minus 0.7 Celsius (31F) on the 21st to minus 4.3 Celsius (24F) on the 18th. A total of 12 ground frosts occurred, and that’s 1 below the average. Each night between the 17th and 23rd had air frost and grass frost, with 6th, 10th, 26th, 28th and 31st also having grass frosts. The cold spell around the third week had the lowest grass minima, with minus 5 Celsius (23F) on each night. The lowest value was minus 7.2 Celsius (19F) measured on both the 17th and 18th.
Rain
Rainfall in January amounted to 115.8 millimetres (4.6 ins.), which was double the monthly average. It was the wettest January for 6 years. Measurable rain fell on 17 days, which was 1 day below the average, and wet days (when 1 millimetre (0.04 ins.), or more, of rain falls) numbered 14, which was 1 day above the average. Steady rain fell during the afternoon and into the evening of the 1st producing a total of 5.8 millimetres (0.23 ins.). Rain then fell at times on each of the following 14 days. Some of the rain was quite heavy, with 8.2 millimetres (0.32 ins.) measured on the 3rd and 5.8 millimetres (0.23 ins.) on the 7th. However, the heaviest rain of the month occurred during the 6 day period commencing on the 10th. A total of 80.6 millimetres (3.2 ins.) were recorded with 5 of the 6 days having over 10 millimetres (0.4 ins.) of rain. The highest daily totals were 17.0 millimetres (0.67 ins.) on the 13th, and 28.6 millimetres (1.13 ins.) on the 15th. The second half of January was completely different. Pressure rose steadily from the 16th and measurable rain only fell once, although melted frost added 0.2 millimetres (0.01 ins.) to the total on the 20th. The only day with measurable rain was the 25th when a wet evening gave 2.8 millimetres (0.11 ins.).
Hail
Small hail fell on 3 days during January. On the 8th, showers were accompanied by hail mid-afternoon and again in the late evening. A heavy, squally shower late on the evening of the 12th contained hail, and hail was also observed in a mid-afternoon shower on the 15th.
Thunder
There was heard on 2 days during January. A short-lived thunderstorm occurred on the afternoon of the 11th, and on the 12th, there were 2 rumbles of thunder in the late evening.
Snow
There was no sleet or snow observed in this part of Shoreham.
Wind
In the first half of January, southwesterly winds dominated on every day except the 2nd, when northwesterlies blew. During the second half of the month, winds were more variable with a slight dominance of winds from the northwest. The first half of the month was often very windy, whereas in the second half of the month winds were much lighter. At Shoreham Airport, the 1st was breezy, but the first gusts above 30 knots (34 mph) occurred on the afternoon of the 3rd, these peaking at 36 knots (41 mph) in the early evening. The brisk southwesterlies continued through the 4th with 37 knots (42 mph) recorded just before dawn. After somewhat of a lull during the 5th, a gust of 31 knots (35 mph) was registered early on the 6th. The 7th was windy all day, with the southwesterlies producing a peak gust of 44 knots (50 mph) in the early evening. Many gusts over 30 knots (34 mph) occurred on the 8th, with the highest of 36 knots (41 mph) occurring in the late evening, followed by a gust of 34 knots (39 mph) occurring just after midnight on the 9th. Gusts of 34 knots (39 mph) occurred again in the afternoon and evening of the 10th. A gust of 46 knots (53 mph) occurred early in the evening of the 11th, with 45 knots (51 mph) measured early on the 12th during this especially windy spell. The 13th was breezy until late afternoon with several gusts of 33 knots (38 mph). The 14th was windy, particularly during the morning with gusts of 40 knots (46 mph) observed. Early on the 15th, southwesterly gusts of 33 knots (38 mph) occurred, but winds veered westerly in the afternoon and became much lighter. As pressure built rapidly on the morning of the 16th, northwesterly increased to strong for a while with gusts peaking at 31 knots (35 mph), but during the rest of the month there were no further gusts above 30 knots, (34 mph) and not that many over 15 knots (17 mph).
Fog
There was mist and morning fog on the 5th, and it was also very misty at times on the 25th.
Statistics for January 2023
| Reporting Site | Highest Temp | Lowest Temp | Rain Total (mm) | Wettest | Rain days |
| Shoreham A/P | 12.2 | -5.2 | * | 38 | 20 |
| Thorney Island | 12.6 | -4.9 | * | 38 | 21 |
| Gatwick A/P | 13.0 | -7.4 | * | 28 | 18 |
| Herstmonceux | 12.0 | -4.5 | * | 59 | 19 |
| Bournemouth (Hurn) | 13.3 | -7.7 | * | 72 | 20 |
| Middle Wallop | 12.9 | -6.7 | * | 42 | 22 |
| Dieppe | 13.5 | -0.8 | 69 | 12 | 19 |
* Totals unreliable