September 2015 Summary

In Brief:
Fine for the first ten days and in the final week.  Unsettled in between.  Cooler than usual by day and night.

Temperature [Minimum]:
On the night ending 26th the temperature fell to 7.6 degs C, which was the coldest September night since 6.8 in 2010.  The highest minimum of the month was 15.1 degs C on the night ending 11th. There has been a milder night than this every September since 2008.
The average minimum for September 2015 was 11.22 degs C, this being the lowest at this location since at least 2004.  Previously the lowest had been 11.59 in 2008.

Temperature [Maximum]:
The coolest day of September 2015 was the 14th with 15.6 degs C.  This was the lowest September max since 15.5 in 2012.  The warmest day of the month was the 10th with 20.6 degs C.  This is the lowest September max since at least 2004.  Previously the lowest had been 21.1 in 2011.
The average maximum for September 2015 was 18.07 degs C, this being the lowest at this location since at least 2004.  Previously the lowest had been 18.83 in 2011.
The temperature exceeded 20 degs C on two days in September 2015, which is the fewest in any September since at least 2004.  Previously this had been 4 days in 2011.
The last time the temperature exceeded 25 degs C in September at this location was in 2006.
It is probably now safe to say the temperature will not exceed 25 degs C at this location at all in 2015.  The last time this happened was in 2011.

Rain:
68.6 mm of rain fell during September 2015, which compares with 181.7 mm in August 2015, and 4.6 mm in September 2014.  As September 2014 was the driest month ever at this location [since at least 2008], it is probably useful to note that of the last eight Septembers, five have had totals between 63.8 and 72.3 mm, and therefore the amount of rainfall in September 2015 was quite normal, despite a massive increase on last year.  September 2015 was also the driest month since June 2015.
The wettest day of the month was the 13th with 20.8 mm, which was the wettest September day since 2012.
There were 16 completely dry days, and 19 with no measurable rain.
There was no measurable rain between the 3rd and 10th and from the 25th.
The wettest spell of the month was from 11th to 15th, when 52mm of the 68.6 total fell.


Cumulatively 858.0 mm of rain has fallen from January to September 2015.  This compares with 870.5 mm during the same period in 2014 [-1.44%].  It is somewhat interesting that 2015 has now almost 'caught up' with 2014, when the excpetionally wet start to 2014 is considered. 

Thunder:
There was no thunder heard at this location during the month, although personally I experienced some during a thunderstorm in North Kent on the 22nd!