Sunday 17th May
The bright and sunny start to Saturday was soon obscured by advancing cloud from a weather front heading in from the west. The increasing cloud meant the temperature by day was still depressed with a maximum of only 13.7C, being 3.6C below average, whilst the UV level of 3.8, a Moderate level, was limited. The rain radar indicated the rain area thinning as it approached southern England and breaking up, which was the reason the precipitation was just 0.2mm in a very light and brief shower at 15.40. The first signs in a turnaround in temperatures was observed last night with a minimum of 6.7C at 05.26, just after sunrise in Marlborough at 05.13. This low was just 0.3C below average and made it the warmest night since the 10th.
The reason for the first signs of a less cold weekend was due to the significant change in wind direction coming mainly from the west rather than the very cool air previously on a northwesterly breeze.
Sunday arrived with variable cloud and thus variable sunshine that had lifted the temperature to 9.8C at 08.00, the warmest start to a new day at that time since the 10th.
Changes in warmth will continue as the wind backs a little further to come from the southwest for the next two days, before coming from a significant southerly direction by Tuesday. The nights will be less cold, in fact perhaps close to or above average. It will take until Tuesday before the daytime temperatures reach average for May and then continue to rise daily as we approach next weekend.
The forecast charts indicate that Tuesday will be a very windy, wet day as a depression closes in from the Atlantic bringing the warmer air, however, ahead of it will be two weather fronts likely to produce significant rainfall. The total rainfall for May is just 10.8mm compared to my 42-year average of 59.5mm. By contrast, we have lost 45mm of equivalent rainfall this month due to evaporation from ground sources and plant life.