It was a dry and sunny month with slightly
above average temperatures and less windy than usual.
The total rainfall of 23.0 mm was only 33% of the 30 year average for the
month. It was the driest September since only 10.8 mm was recorded in 2014.
The average temperature of 15.9°C was the warmest September since 17.1°C in
2016. 2020 was 0.6°C above the 30 year average. The average maximum
temperature was 1.2°C above average whilst the average minimum temperature
It was 3rd sunniest September with regard to the average solar radiation and
at 48.6% of the maximum sunshine it was equal 2nd sunniest
with data starting in 2005.
With an average wind speed of 3.7 mph for the whole month it was the calmest
since 2015 when the average wind speed was 3.3 mph.
The lowest daily minimum temperature of 4.2°C on the 28th is the same as the
previous two September's and the lowest since 3.7°C recorded on 24th
September 2003. The highest daily maximum temperature of 29.2°C on the 14th
was the 2nd highest since records began in 1937. The highest was 31.8°C for
a September occurred in 2004 but there is some doubt about this record.
The summer of 2020 was the 12th wettest in 139 years of data for Bristol
with a total of 311.3 mm when the long term average is 201.9 mm.
It was also the 17th warmest summer in 130 years of data. At 17.8°C it was
1.3C above the long term average of 16.5°C.
2019 Annual summary is here:
For the full monthly summary please go here:
Meteorological site is situated in an urban housing area approximately one
mile to the south of the Centre of Bristol.
This area is in a district called Totterdown.
Statistical correlations with the Bristol
Meteorological Office site, that was
less than two miles to the North and was
situated on top of a City Centre office block, were generally good with
rainfall and barometric data particularly close.
The site of the station is approximately 34 metres above sea level with the
manual instruments mounted in a Stevenson screen. The screen is sited
centrally in a small concreted garden area. A Snowdon
rain gauge is mounted correctly in the ground but does not have the full open
space required around it. A Davis
Vantage Pro2 Plus automatic weather station (AWS) was
added in May 2005 and this is mounted 4 feet above a concrete shelter. The
wind data is gathered automatically from a Davis Vantage Pro2 Plus anemometer which is
sited 3.3 metres (10 feet) above the house top.
Manual observations are still taken at approximately 09:00 hours GMT every
day for rainfall and cloud cover. Rainfall manually recorded in the Snowdon rain gauge is entered for the previous day. The
wind data is constantly logged and automatically reset at 24:00 hours GMT
every day (in the summer BST -1 hour. The Davis rainfall tipping bucket was recalibrated in November 2005 and is now
consistently under 3% under recording (an improvement from installation in
May 2005 when 10% was more
typically the norm).
Since the arrival of the Davis
Vantage Pro2 Plus equipment in May 2005 temperatures, humidity and barometric
pressure are recorded from the new equipment. These figures will be more
accurate and will be taken at exactly 09:00 GMT (in the summer BST -1 hour)
as the data is now logged to a computer.
By default the Davis
equipment records every parameter for the 24 hour period 00:00 to 23:59 BST
or GMT. Data analysis will enable manual data extraction of temperatures and
rainfall to 09:00 GMT (adjusted in the summer). Due to the 0.2 mm (tipping
bucket) measurements of precipitation recorded by the Davis equipment the
Snowdon rain gauge will still be used due to its greater accuracy (see