October 2011 has been a memorable month for a variety of reasons. It started with a record maximum for October at this station, of 26.7º on the 1st, yet in the middle of the month a chilly maximum of only 10.4º was recorded on the 20th. At the end of the month the minimum temperatures were equal to the average maximum for October, some 7º above the long-term average. The mean temperature for October was 12.1º which is 1.8º above the long-term average.
Until the 24th it was a very dry month and heading for a record for October. However, several days with significant rainfall from the 24th gave a total of 41.2mm, which is 47% of the long-term average and the third driest October since 1984. The wettest day was the 26th with 9.8mm. It is interesting to find that the past twelve months have been the driest twelve-month period since November 1997.
During the latter part of the month, the 27th was a miserable day with zero sunshine and subsequently little solar radiation, giving the lowest values since February 2011.
This will be the sixth year since my station started in 1984 that we have not experienced an air frost in October, though very close to it with a heavy grass frost on the morning of the 20th (minimum air temperature of 0.1º). Previous to 2000 we always experienced air frosts in October with an average of 7 each year.
October 2010 was notable for the increased number and severity of air frosts compared to recent years. There were seven air frosts, the highest frequency since 2003, and only one less than the record of eight in 1997. The lowest temperature was -3.9°C in the early hours of the 21st, this being the coldest October night since 2003, the record being -5.1°C in 1992. The beginning of the month was quite warm with mist and fog early in the day but also considerable rainfall, the maximum for the month was 16.6mm on the 1st.
The mean temperature was exactly 1°C below the long-term average. The mean maximum was 0.4°C below the long-term mean and the mean minimum 1.6°C below the long-term average. The total rainfall of 60.3mm was only 68% of the long-term average.
October brought us a variety of weather, from strong winds at the beginning and end of the month with intermittent dry spells and some periods of heavy rain. Some nights were topsy turvy with the thermometer rising over 4°C during the hours of darkness. From the 12th to the 14th we enjoyed a period of glorious sunshine, around 7 hours on some days, accompanied by light winds. However, cloud trapped under the high pressure arrived on the 15th, often referred to as anticyclonic gloom. The last ten days brought winds from a southerly direction, all the way from the Azores, which produced maxima well above the average for late October. The peak temperature was 18.1°C on the 6th.There were just two nights with frost, -0.5°C and -2.0°C during the early hours of the 13th and 18th respectively.
The mean temperature was 0.4°C above the long-term average and the total rainfall of 73.2mm was 82% of the long-term average. The UV levels are low at this time of the year, the peak occurring on the 3rd with a value of 3.6 MEDs. During this autumn month there were three days with 7.5 hours of bright sunshine, the 2nd, 8th and 12rh respectively.