July 2020:
It was the coolest July since 2015 when the
average temperature was 17.3°C. With an average temperature of 17.5°C in
2020 it was -1.2°C below the 30 year average (1981-2010) for Bristol.
Rainfall in 2020 was close to the 30 year average of 64.7 mm but only 71.8%
of the 10 year average.
There were only 6 days in July when the prominent wind direction was not
from the SW.
The maximum hour watts per square metre (W/m2) of 983.5 at 12:00 GMT on 20th
July was the highest for the month since 1017.0 W/m2 recorded at 12:00 GMT
on July 13th 2006. 2020 is the second highest hourly value for July and July
2006 was the highest.
The maximum pressure on the 12th July of 1028 mb was the highest daily value
since 1034 mb on July 8th 2013.
The highest daily minimum temperature of 17.0°C on the 25th July 2020 was
the lowest since 16.9°C was recorded on July 28th 2011.
The
2019 Annual summary is here:
http://www.bristolweather.org/weather2019annual.htm
For the full monthly summary please go here:
http://www.bristolweather.org/weather2020July.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).