Monthly Summary - September 2010

   September starts the season of Autumn and for the first week of the month, Autumn was the new summer.

   But by the month's end, after a number of westerlies had brought cooler, wetter and changeable conditions, the month ended up as being quite average.

   September began on fine form with a succession of warm and sunny days. An area of high pressure (1024 Mb) covered the UK and brought us light winds (ESE) and clear skies and those warm days. Over the next few days the high pressure moved slightly north to Scotland and then to the east of Scotland and over the north sea and whilst fronts out to the west were making very slow progress towards us, we basked in fine weather.

   The first five days of the month all attained 20.0°c, this in some ways was quite ironic as the summer months had only managed to give us, at most, a run of three successive days over 20.0°c!!

   The total of 26 days to reach 20.0°c this year is well down on the two previous years (33+35).

   The 2nd was the warmest of those days at 22.7°c (72.86°F) - but with clear skies comes cooler nights and and the 1st saw the temp' dip to 4.2°c.

   Even rain (7.4mm) on the 6th/7th kindly fell over night. This was brought by a deep depression that moved north over the UK and also had strong winds.

   The 6th and 7th saw temps fall just below 20.0°c, but the 8th at 20.4°c (68.72°F) climbed over and with the 9th falling just short (but still sunny) the 8th will be the last day of the year to reach that mark.

   We had more rain through the 9-11th as a southwesterly flow began to assert itself, but again this mainly fell during the night-time hours.

   The 12th saw a ridge of high pressure give a cloudy but bright day, but the days were becoming mixed and generally unsettled with frequent showers and windy conditions. Atlantic fronts brought those showers on the 13/14th and gusts upto 40 mph on the 13-15th.

   The 15-17th saw the introduction of a cold northwesterly flow; high pressure (1025 Mb) was sitting west of the UK and low pressure over Scandanavia creating these conditions. It was still windy and temperatures were pegged back to 13-14°c and as these few days progressed the conditions became sunnier. The 17th saw the month's coldest night at 2.2°c (35.96°F) and we just avoided a ground frost at 0.2°c.

   It was a return to a southwesterly from the 18th and further outbreaks of rain from a complex frontal system moving west to east over the country. After a quiet day on the 21st the 22nd/23rd saw the worst of the month's rain.

   An area of low pressure (1006 Mb) west of Eire was moving slowly east which had warm air ahead of it and subsequently it was quite mild, but come the evening, come the rain. 12.6 mm fell on the 22nd (0900-0900hrs) and the 23rd was a rough day with another 16.4mm with the depression moving SE through the county.

   The 24th-27th saw a return to a cold northwesterly flow under a ridge of high pressure, but daytime temperatures now took a tumble. The 24th reached just 11.1°c (52°F) and the 25th was only 11.2°c, but at least the days were generally sunny. The nights were also cold and again we just avoided a ground frost.

   The 27th saw a cloudy and dull day (it was bordering on dark, with the lights on during the day) and this was also the case on the 28+29th; it was all quite miserable. The 28/29th saw further rain (8.6mm and 3.8mm respectively) before the month ended on a reasonably bright note.

   So a good first week was followed by changeable weather, occassionally wet, occassionally dull, cloudy, but also sunny - the average conditions from summer continue into Autumn.

   The Mean Temperature for the month was 12.6°c+     - the Mean Max' was 16.84°c and the Mean Min' 8.36°c.

   We had 0 Air Frosts in the month (59 for 2010) and Grass frosts totalled 0 (93 for 2010).


   * September 10 rainfall was 116.0% of the September average for 07/08/09

   * September 10 was 0.2°c warmer than September 2009 +

   * September saw 17 rain days of which 15 were wet days.

  * The 3 month mean for July/August/September 2010 is                   TEMP'    13.58°c          -          RAIN    254.7 mm

* July/August/September 2009 was TEMP'    14.00°c - RAIN    341.4 mm

* July/August/September 2008 was TEMP'    - RAIN    364.7 mm

* July/August/September 2007 was TEMP'    - RAIN    276.5 mm


* 2010 TO DATE TEMP'    8.74°c - RAIN    461.1 mm

* 2009 Jan - Sept TEMP'    9.74°c - RAIN    791.9 mm

* 2008 Jan - Sept TEMP'    - RAIN    985.7 mm

   + Met office figures for September show that NW England/N. Wales had a mean temp' of 13.1°c, some +0.7°c warmer than the reference period 1971-2000 (+0.8°c warmer than reference period 1961-90)


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