Monthly summary September 2009

September has been such a contrast to previous months. A mild first eight days, with the wettest day of the month on the 3rd (8.3mm) changed when the jet stream at last moved north allowing pressure to build. The downside was the arrival of strong northeasterly winds, a maximum gust of 31mph occurred on the 16th, which were unpleasant and lasted until the 19th.  A light shower was noted on the 22nd and 23rd with the remainder of the month being warm and dry with very pleasant autumn sunshine.

The average temperature was 0.2° above the long-term average with no air frosts but a minimum of 2.7°C on the morning of the 27th. This was the driest September I have recorded and is identical to September 2003, which also had a total of 11.1mm and is just 17% of the long-term average. The figure for evapotranspiration, the amount of moisture that evaporates form the ground and plant life, was 59.2mm and explains why the ground is now so dry after a wet summer.