September 2011 was the warmest for four years and the fourth warmest September I have recorded. The mean temperature of 15.0°C was 1.2°C above the long-term average. The month ended with a mini-heat wave when the thermometer peaked at 26.6°C on the 29th and just lower than this on the following day with 26.4°C. This was brought about by a large high pressure area to the east of us allowing very warm and dry air to flow north from the Mediterranean. This system became a blocking high stopping weather fronts from making progress from the Atlantic. A record was set for this station on the 10th when the minimum temperature was a very warm 16.4°C., which was warmer than three of the day time temperatures in the month. It was also a relatively dry month; the total of 46.9mm was 74% of the long-term average. After a warm start for the first two days we had nine successive days of rainfall, but no great daily totals. The wettest day was the 18th with 8.1mm.
Monthly summary August 2011
August 2011, after a warm start, 28.0°C on the 1st and the hottest day of the month, proved to be very disappointing. With much cloud and several very wet days the mean temperature was 0.5°C below the long-term average (maximum was -1.4°C). A record was set on the 18th when the maximum temperature was a miserable 12.5°C, the coldest August day I have recorded since the station started in 1984. There were only 13 totally dry days and the total rainfall of 79.5mm was 126% of the long-term average. There were two notable very wet days with 16.2mm and 13.6mm on the 18th and 26th respectively.
The summer of 2011 was also disappointing. The mean temperature was 0.7°C below the long-term average and the total rainfall of 192mm was 108% of the long-term average.
Monthly summary July 2011
July 2011 was the coldest since 1993. Both the mean maximum and mean minimum were 1.2°C below the long-term average. The warmest day was the 4th with a maximum of 24.7°C but this is only 3°C above the mean for the month. There were several cool nights with the lowest dropping to just 3.9°C in the early hours of the 14th. The rainfall totalled 49.5mm, which is 83% of the long-term average. Interestingly the number of wet days, defined as a daily total equal or greater than 1mm, has risen since the 1980’s from an average of 8 per month to 10. The maximum daily total was 14.5mm on the 16th.
Dry spring 2011
I have commented in earlier reports on the dry spring. It is well known that in such periods of low rainfall plants set their seed much more quickly. For several years I have kept details of when I plant and harvest my broad beans. The number of days has varied between 92 and 99 days but this year the beans were ready for picking in just 69 days, a significant reduction.
Monthly summary June 2011
June 2011 was a cool month and also broke the trend of three consecutive months with below average rainfall. The mean temperature was 14.3°C which is 0.6°C below the long-term average. There were two brief periods (2nd – 4th and 25th – 27th) when we enjoyed warm weather with a maximum of 27.2°C on the 27th. The record for June stands at 31.6° which was recorded on June 30th 1995.
The rainfall of 63.1mm was 115% of the long-term average. Looking at the rainfall data for the first six months of the year I find that 2011 was the sixth driest I have recorded since my station started in 1984.
The solar radiation was 17% below the figure for 2010.
In a previous email I referred to my anemometer (it is sited at the top of a four metre pole that is fixed permanently above the ridge of the bungalow), which had been attacked by a rook. During June there were three nights when the wind dropped out and the instrument was disabled. This time the culprit/s were spiders which overnight had tied up the anemometer and wind vain. It takes a surprisingly strong gust of wind to break the gossamer threads so I have to free the instruments by standing tip-toe on a wall whilst holding at arms length an eight metre fibre-glass pole.
