Author: Eric Gilbert

With the lack of rainfall regularly in the news and the local River Kennet drying up above Marlborough, it was disappointing to find that the rainfall for February was just 29.3mm which is only 45% of then long-term average, the driest since 1998 and the fourth driest I have recorded. The wettest day on the 4th brought 13.6mm, almost half the month’s total. February 2012 was the ninth below average monthly rainfall in the last twelve months. Compounding this situation I find that the total rainfall for the winter 2011/2012 was 188mm, which is only 78% of the long-term average and the sixth driest winter on record. The rule of thumb, when rainfall is considered to percolate through to the aquifers rather than evaporate, is from mid-October to mid-March. With approximately 14 days to go in this period for 2011/2012 I find that I have recorded only 269mm, which is 68% of the long-term average and the third driest on record. The outlook for the summer water supply and the state of the River Kennet gives cause for concern.
The mean temperature for February was 3.0C, which is 1.2C below the long-term average, the coldest since 2006 and the sixth coldest on record. The thermometer dropped to -13.8C in the early hours of the 11th, which is the coldest February night on record. The all time low was in December 1999 with -14.1C. The mean temperature for winter 2011/2012 was 0.5C above the long-term average and the warmest winter since 2007.
The solar energy for February 2012 was 143% of the dull February of 2011.
There were two occasions when snow fell, 4th and 9th, when moderate falls were recorded with an approximate depth of 5cm and 4cm respectively.

For much of the month it seemed as if we had missed winter and had moved into early spring as there were eleven days when the maximum reached double figures [mean maximum over 28 years is 6.5C] and with only a few modest frosts. The mean temperature for the month was 5.17C being 1.3C above the long-term average. It was the warmest January since 2008. The most severe frost was a low of -5.7C in the early hours of the 14th. With air frosts occurring on 9 days this was the lowest total since 2008 and three fewer than the long-term average.
There were elven totally dry days and some useful rainfall although the total at 69.2mm was only 78% of the long-term average. With another month of below average rainfall the fact that evaporation was 133% higher than the two previous years, did not help the groundwater levels. The wettest day was the 3rd when total of 17.2mm was recorded and this coincided with very strong winds gusting to 44mph. Snow fell only on the 30th and with the air temperature at the time just above freezing, did not lay on the ground for more than a few hours and had largely melted before midday.
The winds were quite a feature of the month as maximum gusts exceeded 40mph on each of the 2nd, 3rd, 4th and 5th. The highest gust was recorded at 47mph on the 5th, although this is not a record as a gust of 54mph occurred on 18th January 2007.
Bright sunshine was 134% higher than last year and related to this, was a rise of 120% over the 2011 total, for solar energy, similar to the figure for 2010.

December 2011
This month was in direct contrast to the extremely cold December of last year. The mean temperature was 5.6C which is 1.3C above the long-term average and the warmest since 2006. With the wind predominantly from a westerly direction we had no severe weather and only five air frosts, the most severe being only -3.5C in the early hours of the 10th. The westerlies brought many damp and wet days making it the first month since August with above average rainfall. The wettest day was the 12th with 18.8mm and the total rainfall was 89.5mm, just slightly above the long-term average of 88.4mm. There were three days with snow showers that did not last very long on the ground although the morning of the 17th brought treacherous conditions on paths and roads as a rain shower in the early morning turned into sheet ice as it came into contact with the frozen ground.

2011
The average rainfall in December broke the driest 12-month spell of rainfall since July 1997 but did not alter the fact that 2011 was the driest year since 1996 and the second driest I have recorded.
The total of only 39 air frosts (=<-0.1C) was the second lowest daily count since my records began in 1984 and only two more than the previous record of 37 noted in 2002. Another record for air frosts was set with the latest date for the first air frost of the autumn, which occurred on 23rd November. Previously the years 2004 and 2005 had the latest date for the first autumnal air frost on 13th November. It was the second warmest year since 2006 (10.8C) with a mean of 10.7C, which is only fractionally lower. The third warmest year was 2002 with a mean of 10.6C. The solar energy recorded in 2011 was 5% less than in 2011, the first year that I have been able to keep such records. November produced much less energy than last year whereas December gave an increase of 35%.

November 2011: This month will be remembered for its warmth, lack of rainfall, many overcast days and 6 foggy mornings mid-month. The mean temperature was 9.0°, which is 2.5ºC above the long-term average with a maximum of 15.4º on the 3rd. There were 29 days with a maximum above the mean maximum. The mild conditions also applied to the night-time temperatures with the mean minimum 2.3º above the long-term average. There were just three air frosts when the thermometer dropped to -0.2º, -3.8 and -3.6º on the 23rd, 28th and 29th respectively. The rainfall was only 43.2 mm being 47 % of the long-term average and the third successive month with significantly below average amounts.

Autumn 2011: The statistics give a similar picture of mild weather with below average rainfall. The mean temperature was 1.8° above the long-term average and the 2nd warmest that I have recorded after 2006. The rainfall total produced a more dramatic variation from the mean, as the total of 131.3 mm was only 54 % of the long-term average, being a shortfall of over 100 mm from my 27-year average.

Annual Rainfall: The total rainfall of 603mm, for the twelve month period ending in November 2011, was the driest since June 1997 (584mm). The record low is for the period ending in April 1997 with just 513mm.