A warm, but occasionally wet, month

Temperatures

The average maximum temperature during May 2017 in Shoreham was 18.8 Celsius (66F), and that was around 2 Celsius (3.5F) above normal for the time of year. The average minimum temperature was 10.3 Celsius (50F), and that was nearer 1 Celsius (1.8F) above the normal May value.
The highest temperature recorded during the month was 28.1 Celsius (82F) on the 26th, but there were several other warm days, more especially in the latter part of the month. There were 10 days when the temperature exceeded 20 Celsius (68F), but only 1 of these warmer days occurred before mid month. The temperature reached 22.1 Celsius (72F) on the 11th, but this value was exceeded 5 times during the last 10 days of May, and included highs of 26.3 Celsius (79F) on the 25th and 24.2 Celsius (76F) on the 28th. There were no particularly cool days during May. In fact, the only 3 days with maximum temperatures below 15 Celsius (59F) all occurred before the 9th. These rather cool days were the 1st, 3rd and 8th, with the 3rd having the lowest temperature with a reading of 12.6 Celsius (55F).

There were many mild nights during May. but although there were 16 nights with minima above 10 Celsius (50F), only 4 of these milder nights had lows above 13 Celsius (55F). All of these mildest nights occurred after mid month and included minima of 15.5 Celsius (60F) and an exceptionally mild 17.2 Celsius (63F) on the following night. On the first 11 nights of May minimum temperatures were below 10 Celsius (50F) with only 4 of these cooler nights thereafter. There were only 3 nights when the temperature fell below 7 Celsius (45F). On the 20th a minimum of 6.5 Celsius (44F) was recorded, with 4.7 Celsius (41F) and 3.1 Celsius (37F) measured on the 9th and 10th respectively.
The sea temperature was 11 Celsius (52F) rising to 13 Celsius (55F) towards the end of the month.

Frost

There were no frosts in Shoreham during May, although the grass temperature fell to 0.0 Celsius (32F) on the 10th, and below 3 Celsius (37F) on the 20th.

Rain in Shoreham

There were 64.4 millimetres (2.5 ins.) of rain during May, and that was about 20% above average. Rain fell on 12 days, close to what one would expect at this time of year. Although measurable rain fell on the first 3 days of May, it only amounted to just over 3 millimetres (0.1 ins.). The following week was dry, but then the weather became very unsettled. Between the 11th and 19th, only the 15th had no rain* On the 11th, over 5 millimetres (0.2 ins.) of rain fell, and although rainfall was lighter on the following 3 days, the 4 day period 16th to 19th was very wet. A total of nearly 43 millimetres (1.7 ins.) fell in 96 hours and included 3 days with totals above 10 millimetres (0.4 ins.). The wettest day was the 16th with 14.0 millimetres (0.55 ins.). There was plenty of dry weather for the remainder of the month, and only the 28th had measurable rain. On that day 7.4 millimetres (0.3 ins.) was measured.

*A rain day is from 0900-0900 UTC

Hail

There was a report of hail around lunchtime on the 19th, and although the fall was brief in Shoreham, it was heavier and more prolonged over the Downs to the east of the town.

Thunder

There were 3 days when thunder was observed in Shoreham. There was thunder and lightning from high-level cloud in the early hours of the 27th, with another rumble around breakfast time. Very little rain fell during these storms. On the following evening, storms spread north from France, and although the main centres of activity seemed to be southeast of Shoreham, thunder and lightning continued into the early hours of the 29th.
Wind

The wind through the first fortnight of May was often from a northeasterly direction, but apart from the 2 very warm days later in the month, the northeasterly breeze gave way to the more typical southwesterlies. Generally the wind was light or gentle. and only the 4th and 6th had gusts exceeding 15 knots (17 mph). On both these days 17 knots (19 mph) was measured.

Fog

There was no fog observed in Shoreham during May, although visibility was significantly reduced under low cloud cover early on the 27th.

Statistics for May 2017