The month was noticeable for the relatively high average air pressure with the minimum not falling below 1000.0 Mb. This resulted in 17 totally dry days and when rain fell the daily totals were not large – 8.0mm on the 14th being the wettest day. With the rainfall for the month totalling just 31.7mm, being 52% of the long-term average, it was the driest May since 1998. Most of the shower activity centered around the 14th – 19th due to low pressure to the west of the country. As pressure rose again from an Azores high, temperatures picked up and brought glorious hot, sunny weather to conclude the month although maxima were trimmed due to brisk easterly winds. There were two nights with minimal air frosts on the 4th and 10th. May 2009 produced the 14th consecutive month with above average temperatures (+0.7°C) with the hottest day being the 29th when the thermometer peaked at 24.6°C.
The weather station of Marlborough, Wiltshire
