Daily Report for 21st July 2023

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 11.1 °C (-3.5) 05:54 13.9 °C (-0.1) 16.8 °C (+2.2), 2018 9.7 °C (-4.9), 2020
Maximum Temperature 19.9 °C (-3.4) 15:10 22.4 °C (-0.6) 29.9 °C (+6.6), 2021 19.3 °C (-4.0), 2011
Mean Temperature 16.5 °C (-3.5) 18.2 °C (-0.4) 23.2 °C, 2021 14.9 °C, 2011
Minimum Humidity 58% 15:27 54% 67%, 2011 34%, 2010
Maximum Humidity 84% 06:16 90% 95%, 2009 76%, 2010
Mean Humidity 70% 73% 88%, 2011 53%, 2010
Minimum Pressure 1015 hPa 14:51 1011 hPa 1026 hPa, 2020 1003 hPa, 2009
Maximum Pressure 1016 hPa 23:53 1017 hPa 1028 hPa, 2020 1009 hPa, 2010
Mean Pressure 1015 hPa 1014 hPa 1027 hPa, 2020 1007 hPa, 2010
Mean Wind Speed 3.8 mph (-0.5) 6.0 mph (+1.7) 6.9 mph, 2015 1.1 mph, 2021
Maximum Wind Speed 14.3 mph 19:08 15.2 mph 16.0 mph, 2017 6.6 mph, 2018
Maximum Gust 19.6 mph 19:09 23.7 mph 24.1 mph, 2017 10.2 mph, 2012
Mean Wind Direction NW
Rainfall 0.0 mm 32.6 mm (105%) 4.1 mm, 2011
Maximum Hourly Rain n/a 3.6, 2011
Maximum 10-min Rain n/a 1.6, 2011
Maximum Rain Rate n/a 30, 2011
Minimum Dew Point 8.0 °C 05:36 10.7 °C 15.5 °C, 2021 6.7 °C, 2020
Maximum Dew Point 12.2 °C 15:09 15.0 °C 20.9 °C, 2021 9.7 °C, 2020
Mean Dew Point 10.8 °C 12.9 °C 17.9 °C, 2021 8.2 °C, 2020
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 11.1 °C 05:55 14.1 °C 17.9 °C, 2010 9.7 °C, 2020
Day Maximum (09-21) 19.9 °C 15:11 22.4 °C 29.9 °C, 2021 19.3 °C, 2011
Max 10m Temp Rise 0.6 °C 09:19 0.7 °C 0.9 °C, 2012 0.4 °C, 2011
Max 1hr Temp Rise 2.7 °C 09:48 2.1 °C 3.3 °C, 2018 1.5 °C, 2011
Max 1hr Hum Rise 6% 01:38 11% 16%, 2010 6%, 2013
Max 10m Temp Fall 0.4 °C 16:05 0.6 °C 0.6 °C, 2009 0.3 °C, 2016
Max 1hr Temp Fall 1.7 °C 01:30 1.9 °C 2.4 °C, 2020 1.1 °C, 2016
Max 1hr Hum Fall 8% 10:12 11% 17%, 2012 6%, 2022
Max 10m Wind Speed 9.2 mph 19:15 11.4 mph 11.8 mph, 2015 3.4 mph, 2009
Minimum Feels-like 11.5 °C 05:48 16.0 °C 20.9 °C, 2021 8.6 °C, 2020
Maximum Feels-like 22.3 °C 15:09 25.6 °C 37.5 °C, 2021 21.8 °C, 2012
Mean Feels-like 18.1 °C 21.0 °C 29.2 °C, 2021 17.1 °C, 2012
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 8.8 °C (+0.1) 8.4 °C (-0.5) 13.3 °C (+4.6), 2021 6.2 °C (-2.4), 2011
Humidity Range 26% 35% 51%, 2018 26%, 2023
Pressure Range 2 hPa 5 hPa 11 hPa, 2009 2 hPa, 2023
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 6 [41%]103 hrs (77%) [33%] 13 [89%], 2021 0.2 [1%], 2011
Wet Hours 037 hrs (161%) [7.3%] 4, 2009 0, 2010
Cloud Cover unknown
Events None
Comments blr
Extra Comments
Issues None known
Observer Absent? No
Pond Temperature (Heath) 20.6 °C
Notes
Times of extremes are computed using the midpoint of the longest continuous period at that extreme value.
Cumulative anomalies are reported according to the expected value for the month-to-date rather than month-end.
Sun hrs are initially pulled from the official weather station at Heathrow, and later adjusted by hand to reflect local conditions based on webcam observations. Wet hrs are dervied algorithmically from rainfall data, though may be adjusted manually. Cloud cover and Events are manually reported, often with multi-week delays.
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Daily Graph of Conditions

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Webcam Summary of Cloud Conditions

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