Today the morning broke with sunshine after a chilly night when the thermometer dropped to 4.2C. This followed two mild nights and yesterday with no strong sunshine and a maximum of just 13.9C.
The rain started just after 3.00am yesterday and was almost continuous until just before midnight producing a total of 21.4mm. As a consequence of the thick cloud cover and warm southerly air the thermometer did not drop below 14.2C overnight.
The anticyclone has now departed and low pressure accompanied by weather fronts has brought a mild night, with a minimum of 12C and 2.8mm of rainfall. The temperature at 0800 was 14.7C, the warmest morning at this time of day since 23rd August.
The first two days of October continued under the anticyclone producing 10.2 and 9.8 hours of strong sunshine. This raised the maximum temperature to 2C above the long-term average for the month.
Overnight, as the thermometer dropped to 2.2C, fog formed and at dawn visibility was down to 100m.
Having entered the season of Autumn on the 1st September, meteorologically speaking, I like the quotation from Percy Shelley (1792-1822), who wrote “In the garden, Autumn is, indeed the crowing glory of the year, bringing us the fruition of months of thought and care and toil. And at no season, safe perhaps in Daffodil time, do we get such superb colour effect as from August to November”.
The variability of our weather is often a talking point and September 2015 is no exception. We all realized that the nights were cool but the statistics confirm how cool. The daytime mean was 0.8C below the 31-year average but the nights were 2.5C below. Combining the two I find that the mean for September was 12.2C, which is 1.7C below the long-term average being the coldest September since 1993 and the third coldest I have recorded since my records began in 1984.
We usually enjoy temperatures into the high 20’s for several days in September but the warmest days were the 11th and 12th with a maximum of 21.1C. As regards the lowest temperatures, we experienced a grass frost on the morning of the 27th with a minimum air temperature of 1.4C.
Turning to rainfall, September 2015 has followed the trend of drier than average over the past six years. The total precipitation amounted to 52.2mm, which is 84% of the long-term average or 10mm below. There were many days with modest rainfall totals but just two days, 14th and 16th produced two thirds of the total with 15.2mm and 19.3mm respectively.
It is interesting to note that the evaporation from the ground, plants and water sources amounted to 53.2mm, which is 1mm greater than the total rainfall for September.
The especially cool nights meant that the soil temperature at a depth of 5cm was 1.3C lower than last year.
The anticyclone that develop over the United Kingdom for the last week brought welcome sunshine, warmer days and increased solar activity. The last eight days produced over 58 hours of strong sunshine and maxima closer to, but not above, the long-term average.
We all enjoy the rich colours of the changing foliage as autumn progresses, so let’s hope that there are more fine days in which to appreciate them with no autumnal gales to prematurely strip the leaves