Although yesterday was predominantly cloudy strong sunshine broke out late afternoon into the evening amounting to 2.6 hours, which brings the total for May to 118.8 hrs. The late sun pushed the thermometer higher than it had been all day to a maximum of 22.4C at 17.19, which is almost 6C above the long-term average.
The UV level rose to its highest this month just before and after 1pm, well into the ‘Very High’ category.
Another mild night with a minimum of 10.6C just before 4.30am.
The sun broke through shortly after dawn with the temperature rising rapidly to 14.2C at 08.00.
Summary for May 2017
Another record broken!
With March the warmest since my records began in 1984 we have now just enjoyed the warmest May since 1984. Both the average maximum and minimum temperatures were a significant 1.9C above the 33-year average.
There were contrasting days during the month such as 3rd May when the thermometer struggled to reach 11.8C during the daytime being 5C below the average for May. However, during the latter part of the month it redeemed itself as a warm continental airflow raised the thermometer 10C above the average on 25th and 26th with highs of 26.2C and 26.3C, respectively.
The warm continental air meant that we enjoyed several very mild nights with a minimum of 14.9C during the night of the 26th/27th, which was 8C above the 33-year average. By way of contrast, we had the only air frost of the month during the early hours of the 10th, when the thermometer dropped to -1.2C.
May broke the sequence of five successive below average monthly rainfall totals. After May 1st the month brought us nine continuously dry days. But then the sequence changed with eight successive days of rainfall, some very wet such as 16.1mm on the 13th and 21.1mm on the 17th.
The total rainfall for May reached 82.3mm, which is 136% of the 33-year average or plus 21.2mm. What a contrast to the very dry April being ten times that month’s total.
Strong sunshine for the month totalled 119 hours, which is 4 more than the 3-year average since this instrument was installed. However, there were 4 days without any strong sunshine (>100watts/sq.m.).
During the peak sunshine hours the UV level reached into the ‘Very High’ category on 10 days with the highest on the 31st giving a peak reading of 8.9.
It will come as no surprise, that due to the above average temperatures by day and night, the soil temperature at a depth of 5cm was 1.1C above the three-year average since this instrument was installed.
Summary for Spring 2017
The three-month period brought contrasting weather with two dry months but ending with an above average May. The total rainfall of 139mm was 78% of the 33-year average or 39mm below. As a comparison, spring 2000 was very wet producing 279mm and spring 2001 was very dry with just 65mm.
Spring 2017 was the third warmest since 1984, when my records began, with an average of 10.43C. However, this was very close to the average for 2007 at 10.48C and the record spring of 2011 with an average of 10.50C. It is interesting to note that these record spring averages were all in the past eleven years.
There were 357 hours of strong sunshine compared to 336 in 2016 and 398 in 2015.
Temperatures during these three months have varied from a chilly -3.0C in April to the very warm 26.3C just a month later
The comment by Henry Van Dyke underlines the variability of spring: “The first day of spring is one thing and the first spring day is another”.