Monthly Summary for July 2013

July was a month that brought summer weather at last as it was 1.8C above the long-term average; the maximum was +2.9C and the minimum +0.6C. It was the third warmest July I have recorded and the warmest (18.6C) since 2006 (19.97C) and 1989 (18.91C). A maximum of 31.7C on the 22nd was the highest since 2006 when the record for July of 35.9C, was set on the 19th. There were 19 consecutive days without rain, the longest dry spell since April 2007. During this period the evaporation from plants and the ground amounted to over 85mm of water vapour returned to the atmosphere, many days each in excess of 5mm. The total figure for evapotranspiration was 118.7mm, which meant a deficit over precipitation of almost 55mm even though rainfall was above average.
The rainfall total of 63.8mm was 106% of the long-term average and principally due to heavy rain on three days of 18.2mm,17.6mm and 17.1mm on the 27th, 29th and 22nd respectively. July rainfall, although slightly above average, was so much drier than the recent years of 2009 (113mm) and 2007 (127mm). As the anticyclone drifted away during the last week or so, humidity rose as very warm southerly winds brought thunderstorms on the 22nd, 23rd and 29th.
As a result of the persistent anticyclone, solar energy was 125% of the average for recent years and there were many days with high levels of UV that on the 31st produced an extreme value for late July of 10.0 when the average was 7.7.
Early morning fog was noted on two days during the month along with two very misty mornings.

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