Monthly summary October 2009

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.

Monthly summary September 2009

September has been such a contrast to previous months. A mild first eight days, with the wettest day of the month on the 3rd (8.3mm) changed when the jet stream at last moved north allowing pressure to build. The downside was the arrival of strong northeasterly winds, a maximum gust of 31mph occurred on the 16th, which were unpleasant and lasted until the 19th.  A light shower was noted on the 22nd and 23rd with the remainder of the month being warm and dry with very pleasant autumn sunshine.

The average temperature was 0.2° above the long-term average with no air frosts but a minimum of 2.7°C on the morning of the 27th. This was the driest September I have recorded and is identical to September 2003, which also had a total of 11.1mm and is just 17% of the long-term average. The figure for evapotranspiration, the amount of moisture that evaporates form the ground and plant life, was 59.2mm and explains why the ground is now so dry after a wet summer.

Monthly summary August 2009

August was not the anticipated summer month. It started with a very wet and humid period until the 6th, this day being the wettest with a total of 37.7mm; a record amount for an August day since my records began. There was a drier interlude from the 14th to 20th with temperatures near the average, the 19th being the exception when the thermometer soared to 27.1°C, the warmest of the month. The remainder of August was very changeable. The mean temperature was 0.4°C above the long-term average, principally due to the cloudy nights retaining some of the daytime warmth (+1.1°C) whereas the lack of sunshine meant the average maxima was below the long-term average (-0.7°C.). The total rainfall was 79.1mm, which is 130% of the long-term average.

The total rainfall for the summer was 233mm, which is 132% of the long-term average. The mean temperature for the summer was 0.3°C above the long-term average. Analyzing the statistics I find that the mean maximum was -0.3°C due to the variable weather but the mean minimum was +0.8°C because of the increased cloud cover. The mean temperature for this season has seen a gradual increase since my records began in 1984, except for the cold summers of 1993 and 1996. The average in the 1980’s was around 9.4°C but has risen to almost 10.4°C this year.

With the installation of an advanced weather station I now have much more information and analysis of that data. Consequently the layout of the ‘Current Statistics’ and ‘Daily Statistics’ pages has been revised to include the additional information on UV values, Solar Radiation, Humidity and hours of Sunshine.

Monthly summary June 2009

Although the month started with three warm, dry days the next ten days were decidedly cool and wet with the 6th being the wettest day of the month with 9.7m. The coolest night was the 12th when the thermometer dropped to 4.2°C. A warm spell from 13th to 16th was followed by dry, cool days produced by northerly winds. However, summer returned on the 22nd with increasingly hot, although very humid days, and thankfully for gardeners, some useful rain on the 25th. The hottest day was the 29th at 29.5°. The total rainfall was 41.2mm being 73% of the long-term average and the mean temperature was 0.7C above the long-term average.

Monthly summary May 2009

The month was noticeable for the relatively high average air pressure with the minimum not falling below 1000.0 Mb. This resulted in 17 totally dry days and when rain fell the daily totals were not large – 8.0mm on the 14th being the wettest day. With the rainfall for the month totalling just 31.7mm, being 52% of the long-term average, it was the driest May since 1998. Most of the shower activity centered around the 14th – 19th due to low pressure to the west of the country. As pressure rose again from an Azores high, temperatures picked up and brought glorious hot, sunny weather to conclude the month although maxima were trimmed due to brisk easterly winds. There were two nights with minimal air frosts on the 4th and 10th. May 2009 produced the 14th consecutive month with above average temperatures (+0.7°C) with the hottest day being the 29th when the thermometer peaked at 24.6°C.