April 2021:
It was a cool and dry month with above average
sunshine, high pressure and few strong winds.
The rainfall of 18.8mm in 2021 was only 33.3% of the 30 year average for the
month. For 15 consecutive days from the 12th there was no measurable
rainfall. It was the coldest April with an average temperature of 8.7°C
since 7.9°C was recorded in April 1989. 2021 was 4.0°C cooler than April's
2020 average temperature. The average temperature in 2021 was only 0.1°C
warmer that March 2021. The average minimum temperature in 12021 was 2.9°C
below the 30 year average (1991-2020), whilst the average maximum
temperature was only 1,0°C below the average. The average minimum
temperature of 3.6°C was the lowest since 3.3°C was recorded in April 1978.
April 2021 was the 4th joint sunniest since this data started in 2006. At
58.3% of the maximum sunshine it was equal with 2011.
50% of the wind direction was from the North East. The highest monthly
average daily wind speed of 7.1 mph on the 2nd April was the lowest for the
month since data started in 2006. It was the calmest month of any with an
average wind speed of 3.4 mph since April last year.
The average pressure of 1023 mb at 09:00 hours GMT was the joint highest,
with April 2007, since data began in 1994.
Winter 2020/1
The average winter temperature of 6.0°C was close to the 30 year average
(1991-2020) of 5.9°C. Despite some cold spells it was the 33rd warmest
winter in 131 years of data starting in 1890/1.
The total rainfall for the 3 winter months was 318.7 mm. This represents
122% of the 30 year average (1991-2020). It was the 23rd wettest winter
since records began 140 years ago in 1881/2. Comparing the two recent 30
year averages (1981-2010 and 1991-2020) it can be seen that winter rainfall
has increased by approximately 10 mm.
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/weather2021March.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).