Daily Report for 28th September 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 10.6 °C (+0.3) 05:13 13.3 °C (+2.1) 14.5 °C (+4.2), 2014 8.6 °C (-1.7), 2012
Maximum Temperature 17.6 °C (+0.6) 14:30 21.2 °C (+2.4) 24.9 °C (+7.9), 2011 16.9 °C (-0.1), 2018
Mean Temperature 13.8 °C (+0.5) 17.1 °C (+2.2) 18.6 °C, 2011 12.2 °C, 2012
Minimum Humidity 70% 14:34 66% 77%, 2010 47%, 2018
Maximum Humidity 93% 23:43 93% 98%, 2011 84%, 2016
Mean Humidity 83% 82% 90%, 2010 68%, 2018
Minimum Pressure 1011 hPa 23:50 1017 hPa 1035 hPa, 2015 1005 hPa, 2019
Maximum Pressure 1020 hPa 01:58 1022 hPa 1037 hPa, 2015 1010 hPa, 2019
Mean Pressure 1017 hPa 1019 hPa 1036 hPa, 2015 1009 hPa, 2019
Mean Wind Speed 4.9 mph (+1.0) 2.6 mph (-1.3) 9.8 mph, 2016 1.5 mph, 2010
Maximum Wind Speed 15.5 mph 13:56 9.6 mph 21.5 mph, 2016 5.6 mph, 2010
Maximum Gust 25.1 mph 13:56 15.0 mph 30.6 mph, 2016 7.4 mph, 2010
Mean Wind Direction SSW
Rainfall 10.8 mm 40.2 mm (88%) 10.8 mm, 2021
Maximum Hourly Rain 6.9 mm 21:53 6.9 mm, 2021
Maximum 10-min Rain 3.3 mm 21:05 3.3 mm, 2021
Maximum Rain Rate 60 mm/h 21:00 60 mm/h, 2021
Minimum Dew Point 8.5 °C 04:59 11.3 °C 12.6 °C, 2010 4.3 °C, 2018
Maximum Dew Point 13.4 °C 13:01 16.0 °C 18.1 °C, 2011 11.4 °C, 2018
Mean Dew Point 11.0 °C 13.8 °C 14.1 °C, 2014 7.6 °C, 2018
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 10.6 °C 05:14 13.7 °C 15.4 °C, 2017 8.6 °C, 2012
Day Maximum (09-21) 17.6 °C 14:31 21.2 °C 24.9 °C, 2011 16.9 °C, 2018
Max 10m Temp Rise 0.5 °C 10:46 0.6 °C 0.7 °C, 2011 0.3 °C, 2010
Max 1hr Temp Rise 2.0 °C 10:07 2.2 °C 3.4 °C, 2011 1.0 °C, 2019
Max 1hr Hum Rise 11% 17:54 8% 14%, 2012 4%, 2010
Max 10m Temp Fall 0.8 °C 21:11 0.5 °C 0.8 °C, 2012 0.2 °C, 2010
Max 1hr Temp Fall 1.9 °C 21:56 1.6 °C 2.1 °C, 2012 0.7 °C, 2010
Max 1hr Hum Fall 12% 14:34 9% 21%, 2015 6%, 2019
Max 10m Wind Speed 11.8 mph 17:18 7.1 mph 15.9 mph, 2016 4.0 mph, 2010
Minimum Feels-like 11.2 °C 04:54 15.4 °C 17.4 °C, 2014 6.7 °C, 2012
Maximum Feels-like 20.2 °C 14:24 25.6 °C 29.0 °C, 2011 16.9 °C, 2018
Mean Feels-like 15.6 °C 20.5 °C 21.9 °C, 2011 13.0 °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 7.0 °C (+0.3) 7.9 °C (+0.2) 12.3 °C (+5.6), 2011 3.8 °C (-2.9), 2010
Humidity Range 23% 26% 47%, 2011 19%, 2010
Pressure Range 9 hPa 5 hPa 9 hPa, 2021 2 hPa, 2012
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 3 [28%]97 hrs (77%) [30%] 10.6 [99%], 2011 0.1 [1%], 2010
Wet Hours 5
[Mean rain rate: 2.2 mm/h]
29 hrs (76%) [4.3%] 6, 2017 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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Webcam Summary of Cloud Conditions

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