Friday brought us 2.5 hours of strong sunshine with ‘Very High’ UV level reaching 8.4, not seen since 4th August last year.
There was no rain in the past twenty-four hours although the air was humid.
The thermometer was slightly up again on the peak for Thursday with a maximum of 22.2C, being 2C above the June average.
Another mild night followed under a blanket of cloud with the minimum reached just before dawn of 14.3C, which was 4.3C above the 34-year average.
Saturday has seen a brightness under a predominantly cloudy sky with the occasional burst of sun. However, the temperature rose to 16.1C at 08.00.
Summary for May and Spring 2018
May
With a new record temperature and record sunshine, May could well have been a summer month rather than late spring.
The Meteorological Office, in its provisional data, stated that May 2018 was the sunniest since 1929. My sunshine recorder that is triggered when the sun’s strength reaches the standard 100w/sq m., recorded 237.3 hours. The average over the past four years when 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 the 7th 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 the 27th.
There was only one air frost during the month, which occurred on the 1st 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% of the rainfall fell on just four very wet days when storms reached Marlborough. A deluge occurred on the 24th with 31.9mm being recorded with the second wettest producing 9.2mm on the 29th. In contrast 2007 brought 149mm and 1990 just 7mm.
There were 20 dry days during the month with only 5 days classed as wet when the daily rainfall does not exceed 1mm.
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 so no wonder gardens were very dry for most of the month.
From day to day we as humans have to adjust to widely varying temperatures and May was no exception. The variation ranged from just 3C on the 30th to 21C on the 7th.
Hail fell on 1 day, fog was evident on 3 mornings with visibility down to 150mm on two of these and thunder was heard on 3 days.
Spring 2018
Although March was a cold month the following two warmer months resulted in the mean 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.