September 2011 Summary

Summary:
September 2011 was a fairly uneventful month weatherwise.
Annoyingly, a little rain, or drizzle, fell on most days, leading to there being no lengthy dry, fine spells.
There was often a lot of cloud, which kept daytime temperatures rather low, but night-time temperatures relatively high.
The last week, although dry with high pressure, saw a lot of mist and fog, which eventually cleared on most days to leave brighter afternoons. Unfortunately the western proximity of Falmouth ensured that it once again missed out on the fine weather of further east.
This has been a recurring problem of summer 2011, as any high pressure systems that did occur over the UK, were mainly too far east, giving rise to a southerly moisture-gathering airflow, and placing West Cornwall closer to low pressure systems.
One interesting weather feature did occur however - during the late morning of the 9th - another typically misty, overcast and gloomy day - a thunderstorm developed, very rare during these conditions. Most of the associated rain fell further north and east, however there were several instances of thunder and lightning here.

Temperature: Minimum:
Night-time temperatures ranged from 8.9 degs C on the night of the 22nd/23rd, to 16.5 degs C on the 8th/9th [the warmest night since that of the 20th/21st August 2010]. This gave an average of 13.29 degs C - the highest of any month since August 2010, and the second highest of the last eight Septembers, behind 2006.

Temperature: Maximum:
Daytime temperatures ranged from 16.9 degs C on the 18th to 21.1 degs C on the 2nd, giving an average of 18.83 degs C.
Unsurprisingly it was the coolest month since May 2011, however it was also the coolest September of the last 8, although very close to most.
Another feature of the uninteresting nature of the month was that the range of maximum temperatures was just 4.2 degs C. September 2008 had a similar range of just 4.0 degs C.

Rainfall:
72.3 mm of rain fell during the month, comparing to 54.7 in August 2011 and 102.7 in September 2010. It was the second wettest September of the last four, and the wettest month since June.
The wettest day was the 20th when 18.0 mm fell. The wettest spell was from the 3rd to the 6th, when a total of 28.7 mm fell, but outside of that period rain amounts were mostly of the annoying, rather than useful, category.
There were 9 completely dry days, the least since May.
The first two days of the month added to the last five of August to give a 7-day dry spell, and no measurable rain fell on the last four days of the month. Outside of these times, the maximum number of consecutive completely dry 24-hr periods was 2.

Thunder:
A thunderstorm occurred around midday on the 9th.