With a mean temperature 0.9C above the long-term average and the solar radiation total at a peak since 2010, May 2016 was a fairly good late spring month.
There was a very warm period in the second week with a maximum of 26.3C on May 8. However, although there were many days when the thermometer briefly nosed a degree or two above the average there was no sustained period of very warm days.
There were several very chilly nights with a ground frost occurring in the first week, the coldest night was on May 1 with a minimum of -0.7C. May 4 was not much warmer as in the early morning the thermometer dropped to 0.2C.
The rainfall total was 58.5mm, just below the May average of 60.6mm for the last 32 years. There were seventeen dry days and several with modest totals, but the wettest day occurred on May 10 with a considerable daily total of 16.6mm.
It is interesting to see over the years the variation in the monthly rainfall for May: 1990 brought a very dry month with just 6.7mm and in contrast the year 2007 produced 149.5mm.
This being the last Spring month and with many hours of strong sunshine, it is not surprising to find that the total loss of moisture through evaporation from ground sources and plant life was 90.4mm, leaving a deficit of 32mm over rainfall – though not every farmer or race-goer in Wiltshire would believe those figures!
The direct, strong sunshine total of 129.5 hours was the highest since this instrument was installed in 2014.
Although not an unusual occurrence in recent years, there were seventeen days when the prevailing wind was not from the southwest, but a persistent wind blew from the north or northeast. Looking back at the records I see that in 2010 there eighteen such days, in 2012 there seventeen days and in 2014 sixteen.
Spring 2016:
It has been the coolest spring for three years being 0.4C below the 32-year average. The records show that both March and April were 1C below the average, but in contrast May was, as we have seen, 0.9C above the average.
It has been a wetter spring than normal with a total of 203mm, which is 25mm above the 32-year average. Looking back, the spring of 2011 was the driest with just 65mm in the three months, yet the spring of 2000 produced 279mm.