December 2020:
Rainfall at 146.4 mm was 152.2% of the 30 year
average 1981-2010. It was the wettest December since 155.4 mm was recorded
in 2013.
The average temperature of 6.6C was 0.7°C above the 30 year average for the
month. The average maximum temperature for December at 8.8°C was the lowest
since the very cold December of 2010 when the average maximum temperature
was only 3.4°C for the month.
The average pressure of 1002 mb for December 2020 was the lowest since this
data started in 1994.
The low pressure of 967.7mb at 06:00 on the 28th was lowest pressure in
December since 964 mb was recorded 2nd December 2005.
It was the lowest pressure recorded for any month since November 8th 2010
when 963.7 mb was noted.
The lowest daily maximum of 3.1°C recorded on the 28th December was the
lowest for the month since December 2012.
The highest maximum 24 hour rainfall of 29.5 mm on the 26th of December was
the highest for the month since 37.7 mm was recorded in 2013.
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.
The
2020 Annual summary is here:
http://www.bristolweather.org/weather2020annual.htm
For the full monthly summary please go here:
http://www.bristolweather.org/weather2020December.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).