The warm and sunny May in Marlborough brought two more records to add to the 2018 list
With a new record temperature and record sunshine, May could well have been a summer month rather than late spring month.
The Meteorological Office, in its provisional data, found that May 2018 in the UK was the sunniest since 1929. In Marlborough, my sunshine recorder that is triggered when the sun’s strength reaches the standard 100w/sq m., recorded 237.3 hours of sunshine.
The May average over the past four years since this instrument was installed, was 109 hours with 130 hours in 2016.
It is not surprising to find that it was also a very warm month with the mean temperature a significant 1.4C above my 34-year average. It was the fourth warmest since this station started in 1984 with 2017 the warmest. The night-time mean was close to average but the daytime was 2.5C above average.
There was a brief very warm spell just after the start of the month with the warmest day on May 7 producing a peak temperature of 28.1C that set a new record high for May. Another brief very warm spell occurred towards the end of the month with 24.7C set on May 27.
There was only one air frost during the month, which occurred on May 1 when the thermometer briefly dropped to -0.2C.
Rainfall for May totalled 60mm exactly, which was 1.1mm short of the 34-year average. However, 92 per cent of the rainfall fell on just four very wet days when storms reached Marlborough. A deluge occurred on May 24 with 31.9mm being recorded with the second wettest producing 9.2mm on May 29. In contrast 2007 brought 149mm and 1990 just 7mm.
There were 20 dry days during the month. Although rainfall of 60mm was almost average for May, the many very, dry days meant the equivalent rainfall that evaporated into the atmosphere from ground sources and plant life was 97.3mm, giving a deficit of 37.3mm. No wonder then that gardens were very dry for most of the month.
From day to day we humans have to adjust to widely varying temperatures and May was no exception. The variation ranged from just 3C on May 30 to 21C on May 7.
Hail fell on one day, fog was evident on three mornings with visibility down to 150mm on two of these and thunder was heard on three days.
How did Marlborough’s Spring 2018 measure up?
Although March was a cold month, the following two warmer months resulted in the mean Spring temperature being 0.5C above the 34-year average. Spring 2017 was 1C cooler, but 2016 was 1C warmer.
The upward trend in the spring mean temperature is slowing as can be seen in the following data. Taking 10-year bands since 1984, which was in the middle of a cold spell, the mean has risen from 7.8C to 8.5C and most recently 8.8C.
The three months gave a rainfall total of 254mm, which was 77mm above the long-term average and the wettest since 2008 with only three wetter since 1984. The extremes were set in 2000 with 279mm and the dry spring of 2011 with only 65mm.
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