August 2021:
The average temperature was -0.8°C the 30 year
average for Bristol and was equal coolest at 17.3°C with 2017 since 2015
with 17.2°C.
The average maximum temperatures were 1.2°C below the 30 year average
(1991-2020) but average minimum temperatures were only 0.2°C below.
It was the dullest August since 2015. The maximum percentage of sunshine in
2021 was 43.7%, 5% below the average 2005-21. There were an unusually high
number of NE winds for the month.
The total monthly rainfall for August was 86.3mm which is 104% of the
average for the month.
During the first week in August 2021 there were 4 spells of rain, totaling 7
hours, that delivered 44.8 mm of out of a total of 64.6 mm of rain for the
week.
This is very unusual for this site in urban Bristol at any time of the year.
The first spell was 14.6 mm between 15:20 & 17:20 on the 2nd of August.
The second spell was 12.4 mm between 18:50 & 20:50 on the 5th. The third
spell was 7.4 mm between 13:40 & 14:40 and finally
the fourth spell was 10.4 mm between 03:20 & 04:20 all falling on the 7th.
The 28.9mm of rain recorded in the 24 hour period on the 7th August was the
highest of any month since December 2020 when 29.5 mm was recorded.
The highest daily maximum temperature of 24.1°C on the 14th was the lowest
maximum for an August since 21.4°C in 1993.
There was a large range of pressure as the maximum pressure at 09:00 GMT of
1030mb on the 31st was the highest in August since 2012, and the lowest
pressure
for the month of 994 mb was the lowest since 992 mb in August 2014.
Summer 2021 It
was the 17th warmest in 131 years of complete data for the city of Bristol
without feeling spectacular. With an average temperature of 18.1°C it was
0.4°C above the 30 year average (1991-2020). The warmest summer was 1995
with an average temperature of 19.4°C. The coolest was the summer of
1954 when the average temperature on reached 14.4°C.
It was the 26th warmest summer with respect to maximum temperatures at
22.0°C out of 116 complete years of data. With respect to average
minimum temperatures. The summer of 2021 was the equal 4th warmest (with
1983) at 14.4°
The summer rainfall
total was 222.1 mm which is 10 mm above the 30 year average.
Annual 2020:
In 130 complete years of Bristol's annual average temperatures in 2020 it
was the 2nd warmest with an average temperature of 12.4°C. The warmest was
in 2014 at 12.5°C.
The annual rainfall of 1090.2 mm for 2020 was 123% of the 30 year average
for the city of 889.9 mm. As the next 30 year average is prepared
(1991-2020) 1090.2 mm represents 117% of the new average rainfall as this is
increasing.
The average annual 24 hour maximum rainfall of 21.0 mm in 2020 was the
highest since 23.1 mm in 2012 which was the wettest year on record for
Bristol.
In 2020 48% of all the wind directions were from the SW or WSW. With much
less frequencies Southerlies and North Easterlies were next.
Annual average pressure of 1014 mb, equal with last year, was lowest since
1012 mb in 2014.
2020 was the sunniest complete year of data, at 42.5% of the maximum, with
regard to Wm2, since this parameter started in 2006.
In 2020 there were only 1 day when snowfall was observed to fall and none
had any snow lying at 09:00 hours.
There were 10 days when thunder was heard and there were 7 days when a
temperature of below 0.0°C was recorded in 2020.
To
view a full report of the Bristol Annual Weather 2020 and a discussion of trends
etc click here. This is a Word created .doc document
which is produced annually for a couple of Bristol Naturalist Society
publications. Please acknowledge the source if quoting any of the contents.
Thank you.
The
2020 Annual summary is here:
http://www.bristolweather.org/weather2020annual.htm
For the full monthly summary please go here:
http://www.bristolweather.org/weather2021August.htm
The
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
above).