Yesterday produced another day of considerable rainfall with the heaviest this month of 14.8mm. Being overcast all day, with heavy cloud, it was the lowest figure for solar energy since February 2014. There was no direct sunshine for the second day in November.
Author: Eric Gilbert
-
Analysis of first air frost of every autumn since 1985.
The Intergovernmental Panel on Climate Change in its report this week reviewed the latest scientific evidence for climate change.
I have analysed the evidence for just one aspect of the climate in Marlborough over the last thirty years, namely the date when the first air frost of autumn occurred since 1985.
Taking the years in groups of five since 1985 and then taking an average, the trend in these averages over the last thirty years can be seen. Using the datum of 1st September the average number of days since that date for the first period of 1985-1989 is 30 days or 30th September.
After a slight regression to 28th September for the next five year average of 1990-1994, the trend is then distinctly later in the year. The average for the first air frost of the year moves to 9th October, 26th October, 27th October and lastly to 1st November for the 2010-2014 group of years.
Although memories are fallible and we remember certain mild autumns that we enjoyed over the recent years, the evidence is quiet clear from the data above that there has been a significant shift to a much later date in the year for the first air frost of autumn. -
First air frost of autumn
The thermometer dropped below freezing for a couple of hours around dawn with a minimum of -0.1C. This is the first air frost to occur in autumn 2014, being as late as 4th November
The incidence of the first air frost in autumn has been, on average, getting later over the last thirty years. This is the second latest since my records began in 1984. My records for the 1980s show the first air frost always occurred in September except in 1986 when it was later on 7th October.
A full analysis showing how, on average, this event has moved later in the calendar over the last 31 years will appear in the next few days. -
Summary for October 2014
October 2014 will be remembered for the above average temperatures throughout much of the month but also for the dismal few days from the 12th to the 18th.
The average temperature was 11.99C, which is 1.5C above the long-term average. The extremes were 12.77C in 2001 and 6.95 in 1992. Highlights were the very warm days at the start of the month but the warmest day was on the 31st when the thermometer peaked at 20.7C. The record for this month is a high of 26.7C, which occurred on 1st October in 2011. The warmest night of the month was recorded on the 31st when the thermometer did not drop below 13.8C, which is very close to the average day temperature. The 5th brought the coldest night with a minimum of 0.7C.
With the wind coming from a southerly quarter for 21 days it is not surprising to find that there were no air frosts during the month. Previous to the year 2000 at least one air frost was recorded in each October but in the last 14 years, eight have been free of air frosts.
Rainfall fell predominantly during the first half of the month with large falls of over 10 mm on three days and a maximum of 14.1mm on the 13th. The total rainfall amounted to 92.2mm, which is close to the long-term average of 88.9mm. This total is far less than the heavy rainfall in the previous two years. However, the extremes occurred in 2004 with 159.3mm and in 2003 that was very dry with only 36.8mm. There were only ten dry days during the whole of the month.
Many days were quite windy with four days producing maxima in excess of 30mph. The peak gust occurred on 21st with a maximum of 38mph.
Sunshine amounted to 66 hours during the month. The two sunniest days were 7th and 28th when 6.16 hours and 6.19 hours were recorded respectively. There were six days when no sunshine was recorded, mainly occurring in the middle of the month and the 29th.
