May 2017 summary

This was the warmest May since 2008 with an average temperature of 13.6C, about a degree above normal for this time of year. Rainfall was above average but not exceptional at 64.8mm, with the wettest day being the first with 11.8mm – the same total as we recorded for the whole of April. The following day saw the start of the longest dry spell of the month, with no rain recorded from the 2nd to the 10th thanks to a persistent easterly breeze. Talking of wind, it was a quiet month with a maximum gust speed of 24kts.

Thunderstorms were in evidence on three occasions during the month, with rolls of thunder audible from a storm to the east on the afternoon of the first, a brief storm bringing an end to that dry spell on the afternoon of the 11th, and a spectacular light show around 3am on the 27th when a line of thunderstorms stretching from here to the Isle of Wight lit the sky to the south east. That was, incidentally, the warmest May night we have recorded, with an average temperature of 19.3C – not conducive to sleep.

The highest temperature of the month was 26.7C on the 26th, a day of almost unbroken sunshine – and the source of energy for those thunderstorms the following morning. This wasn’t the only sunny day, with good periods of sunny weather around the 10th and the 19th.

Apart from that dry spell for the first week or so of May, there was no dominant weahter pattern and we alternated between spells of high and low pressure, bringing a mix of weather.

May brought to an end our joint-warmest Spring, with an average temperature of 10.8C matching the figure for Spring 2011. Total rainfall was 125.8mm, below average but with the exceptionally dry April being partially offset by the above-average total for May.