Daily Report for 26th September 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 12.7 °C (+2.3) 02:10 13.5 °C (+2.2) 15.0 °C (+4.6), 2011 6.5 °C (-3.9), 2020
Maximum Temperature 21.4 °C (+4.1) 15:59 21.5 °C (+2.5) 23.8 °C (+6.6), 2018 11.6 °C (-5.7), 2020
Mean Temperature 16.7 °C (+3.2) 17.3 °C (+2.4) 17.7 °C, 2011 9.0 °C, 2020
Minimum Humidity 69% 18:00 66% 75%, 2012 33%, 2018
Maximum Humidity 98% 08:24 93% 98%, 2021 84%, 2016
Mean Humidity 86% 82% 86%, 2021 64%, 2018
Minimum Pressure 1012 hPa 06:20 1017 hPa 1030 hPa, 2018 989 hPa, 2012
Maximum Pressure 1014 hPa 21:02 1022 hPa 1035 hPa, 2018 999 hPa, 2012
Mean Pressure 1013 hPa 1019 hPa 1032 hPa, 2018 992 hPa, 2012
Mean Wind Speed 4.2 mph (+0.3) 2.4 mph (-1.5) 6.5 mph, 2019 1.1 mph, 2009
Maximum Wind Speed 13.8 mph 15:34 9.1 mph 15.3 mph, 2016 4.5 mph, 2009
Maximum Gust 19.4 mph 15:31 14.2 mph 26.5 mph, 2020 6.4 mph, 2009
Mean Wind Direction SW
Rainfall 0.0 mm 26.8 mm (63%) 4.1 mm, 2012
Maximum Hourly Rain n/a 3, 2011
Maximum 10-min Rain n/a 2.5, 2016
Maximum Rain Rate n/a 66, 2016
Minimum Dew Point 11.8 °C 02:01 11.5 °C 13.3 °C, 2011 2.0 °C, 2020
Maximum Dew Point 16.8 °C 12:21 16.1 °C 16.8 °C, 2021 7.8 °C, 2020
Mean Dew Point 14.2 °C 14.0 °C 14.5 °C, 2011 5.1 °C, 2020
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 12.7 °C 02:11 13.7 °C 16.3 °C, 2011 6.5 °C, 2020
Day Maximum (09-21) 21.4 °C 16:00 21.5 °C 23.8 °C, 2018 11.6 °C, 2020
Max 10m Temp Rise 1.0 °C 08:19 0.6 °C 1.0 °C, 2021 0.3 °C, 2020
Max 1hr Temp Rise 2.5 °C 08:59 2.2 °C 3.5 °C, 2018 1.0 °C, 2020
Max 1hr Hum Rise 8% 19:36 7% 15%, 2016 4%, 2020
Max 10m Temp Fall 0.4 °C 17:57 0.4 °C 1.3 °C, 2016 0.2 °C, 2020
Max 1hr Temp Fall 2.0 °C 18:47 1.5 °C 4.0 °C, 2018 0.7 °C, 2020
Max 1hr Hum Fall 8% 13:05 9% 15%, 2018 3%, 2010
Max 10m Wind Speed 10.9 mph 15:42 6.7 mph 12.1 mph, 2016 2.9 mph, 2009
Minimum Feels-like 14.9 °C 01:44 15.7 °C 18.1 °C, 2011 2.0 °C, 2020
Maximum Feels-like 26.4 °C 15:42 25.9 °C 26.4 °C, 2021 11.5 °C, 2020
Mean Feels-like 20.2 °C 20.7 °C 21.4 °C, 2011 8.0 °C, 2020
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 8.7 °C (+1.9) 8.0 °C (+0.3) 16.1 °C (+9.3), 2018 5.1 °C (-1.7), 2012
Humidity Range 29% 26% 58%, 2018 18%, 2012
Pressure Range 2 hPa 4 hPa 10 hPa, 2011 2 hPa, 2021
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]94 hrs (79%) [31%] 10.9 [101%], 2018 0 [0%], 2021
Wet Hours 020 hrs (56%) [3.2%] 6, 2012 0, 2009
Cloud Cover unknown
Events None
Comments blr
Extra Comments
Issues None known
Observer Absent? No
Pond Temperature (Heath) 17.0 °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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