Thursday 21st May
The variable sunshine on Wednesday, especially in the morning, lifted the maximum temperature to a very welcome 1C above the May average with a high of 18.3C at 11.55, before the cloud thickened. However, the highest UV light since the 3rd of August was logged at 13.15 in a burst of sunshine with a value of 6.6 that put it in the ‘Very High’ category. A mild night followed with a low of 10.7C at 01.12 early Thursday, being 3.7C above average.
Thursday began dull and cloudy as a result of cloud that had drifted in just after midnight, that by 01.00 had totally blanketed southern England. The temperature rose over 2C in the early hours to reach 13.3C at 08.00, making it the warmest start to a new day this month. The cloudy conditions are thanks to a warm front that will cross the UK this morning. As the front edges away the high pressure will begin to feed in warmer and drier air from a southwesterly direction, that will see the cloud begin to disperse and the sun to appear towards midday.
The barometric pressure has risen another 11mb since yesterday as the high pressure begins to build over the near Continent and then to dominate our weather over the next few days. The heat will build over the next few days as the warmth is brought up from a warm Continent and as far south as North Africa on a mainly southwesterly breeze, that will be light in strength.
By the weekend the maximum temperatures will be well above the May average, which might be as high as 30C. There has been mention in the media recently of the possibility of a mini-heatwave arriving. The meteorological definition of a heatwave is for at least three consecutive days for the maximum temperature to be equal to or above the heat threshold for a particular area. The heat threshold for Wiltshire is 27C. At the moment the possibility of a heatwave will be from Saturday to Monday, before the extreme heat drops a few degrees, but still hot.
I attach another image from the Bowood House, Wiltshire, woodland walks that have stunning displays of rhododendrons, azaleas and bluebells. There are well-signposted paths showcasing the best blooms and amid the peaceful atmosphere. The Woodland Garden closes on 7th June.