Windrush Weather

March 1, 2011October 23, 2011

Monthly summary February 2011

February 2011 brought us unusual weather for the last month of winter. The mean temperature was 2°C above the long-term average with the mean maximum +1.6° and the mean minimum +2.3°C. The first two weeks brought day temperatures well above the average but fell away when the wind changed to the south-east and then north-east. The total of only five air frosts was well below the average of eleven for February and was the lowest number since 1997. The total rainfall of 74.5mm was 116% of the long-term average and helped to increase the low figure for the winter period. There were only three totally dry days and an unusually high frequency of days (nine) with minimal precipitation of less than 1mm. The wettest day was the 13^th with 20% of the monthly total at 14.9mm.

The period of winter (1^st December to 28^th February) produced a mean which was 1.4°C below the long-term average. The frequency of air frosts was high with a total of 46 which is 12 above the long-term average. The total rainfall was 212mm, which is just 87% of the long-term average.

March 1, 2011October 13, 2011

Wind speeds

I recently decided to analyse my records of wind speeds, the most accurate go back to the year 2000 when my anemometer was moved to a very high position, well above roof height. The initial results gave me concern as recent years have shown a decline in wind speed-readings. I had wondered if the repeated attack on the instrument by a rogue rook, two years ago, had damaged the unit.

My equipment captures data every five seconds and from these records I find that there has been a downward trend in average annual wind speeds since 2007 – the fall being most notable for the last two / three years.

2001	2002	2003	2004	2005	2006	2007	2008	2009	2010
4.3	4.6	4.3	4.3	4.4	4.3	4.1	3.9	3.3	3.1

Looking specifically at readings in the winter (meteorological) period, December 1^st to February 28^th, I discovered a reduction in gusts of 20mph +, by an average of four per year. The statistics for gusts of 30mph + produced a reduction of three per year.

January 31, 2011December 4, 2011

Monthly Summary January 2011

In January 2011 we enjoyed mild if overcast days when the maximum was four to five degrees above the average (12^th and 16^th) or in contrast as on the 29^th when the maximum was only 0°C. Some nights were warm with a minimum of 10.4° and 9.5°C (14^th and 13^th respectively) when the average is 1.3°. A total of 16 nights of air frost was above the average of 11 over the last 27 years with the early morning of the 31^st being extremely cold when I recorded a minimum of -8.5°C. The record stands at -13.3°C in January 2009. The mean temperature was 0.4°C below the long-term average. The frost that occurred in early January gave a coating of ice to everything but the air frost on the 27^th went almost unnoticed due to the dry air prevailing and some air movement (82% humidity as opposed to 98% earlier in the month). There were 12 days without rainfall but on four occasions the daily total was in double figures (18.1mm, 17.4mm, 17.1mm and 14.9mm) with a monthly total of 107.8mm, which is 123% of the long-term average.

January 1, 2011November 28, 2011

Monthly summary December 2010

December 2010 was the coldest December that I have recorded and broke many other records. The mean temperature was 5.2°C below the long-term average. There was a record of 25 days with air frost in the month totaling a substantial 424 hours of sub-zero temperatures. There were ten days when the thermometer did not struggle into a positive figure. The extreme low of -11.7°C in the early hours of the 24^th was the coldest December night since 1999 and the second coldest on record. It was the driest December since 2001 giving a total of 29.3mm, which was only 32% of the long-term average. Snow fell on a total of eight days and we endured ten days of fog.

The year 2010 was the coldest year since 1987 being 1.1°C below the long-term average and produced a record 32 days of snowfall. The total rainfall of 672mm was just 79% (175mm below) of the long-term average. It was the third driest year after 1997 (671mm) and 1996 (594mm).

December 1, 2010November 28, 2011

Monthly summary November 2010

November 2010 proved to be a most interesting month, weather-wise. The first ten days were wet, windy and warm with a maximum of 16.6°C on the 4^th and the warmest night on the 5^th when the thermometer did not drop below 13.4°C although the mean minimum for this month is 3.6°C. The wettest day of the month occurred on the 7^th with 10.5mm although 80% of the total rainfall fell by the 12^th. The contrast began on the 18^th as the winds backed into an easterly then northerly direction for the remainder of the month. The maximum on the 28^th was -1.1°C followed by the coldest night when the thermometer fell to -5.8°C in the early hours of the 29^th. The mean temperature was 1.7°C below the long-term average and the rainfall was 71% of the long-term average.

A number of records were broken this month, since my records began in 1984, with the warmest November day (16.6°C) and the coldest November day (-1.1°C). It was the coldest November since 1993 and the third coldest I have recorded. There were 65 continuous hours of below zero temperatures.

The Autumn of 2010 was the coldest since 1991 being 0.9°C below the long-term average. The total rainfall of 188mm was 77% of the long-term average.