Daily Report for 12th September 2023

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 14.2 °C (+2.3) 23:55 16.3 °C (+3.9) 14.6 °C (+2.7), 2011 8.5 °C (-3.4), 2012
Maximum Temperature 23.2 °C (+3.6) 13:24 27.4 °C (+7.0) 25.8 °C (+6.2), 2022 16.3 °C (-3.3), 2018
Mean Temperature 19.4 °C (+2.9) 21.5 °C (+5.5) 20.3 °C, 2022 13.1 °C, 2018
Minimum Humidity 69% 13:24 57% 72%, 2013 48%, 2011
Maximum Humidity 93% 22:28 93% 97%, 2013 83%, 2012
Mean Humidity 83% 78% 87%, 2018 65%, 2015
Minimum Pressure 1014 hPa 05:50 1017 hPa 1028 hPa, 2009 995 hPa, 2017
Maximum Pressure 1018 hPa 23:49 1021 hPa 1034 hPa, 2009 1007 hPa, 2017
Mean Pressure 1015 hPa 1019 hPa 1031 hPa, 2009 1004 hPa, 2017
Mean Wind Speed 3.3 mph (-0.6) 2.9 mph (-1.0) 10.8 mph, 2011 0.8 mph, 2021
Maximum Wind Speed 11.8 mph 23:33 9.9 mph 22.1 mph, 2011 5.6 mph, 2021
Maximum Gust 18.4 mph 22:47 14.9 mph 37.4 mph, 2011 8.7 mph, 2013
Mean Wind Direction NW
Rainfall 2.4 mm 4.6 mm (23%) 3.1 mm, 2018
Maximum Hourly Rain 1.4 mm 20:50 2.3 mm, 2012
Maximum 10-min Rain 1.0 mm 20:32 2.3 mm, 2012
Maximum Rain Rate 7 mm/h 19:04 60 mm/h, 2012
Minimum Dew Point 13.1 °C 23:56 14.5 °C 13.1 °C, 2022 2.6 °C, 2012
Maximum Dew Point 17.7 °C 00:04 19.5 °C 18.2 °C, 2022 11.3 °C, 2012
Mean Dew Point 16.3 °C 17.1 °C 16.3 °C, 2023 6.7 °C, 2012
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 17.7 °C * 07:07 16.6 °C 17.7 °C, 2023 8.5 °C, 2012
Day Maximum (09-21) 23.2 °C 13:25 27.4 °C 25.8 °C, 2022 14.6 °C, 2018
Max 10m Temp Rise 0.5 °C 10:49 0.6 °C 0.9 °C, 2022 0.3 °C, 2018
Max 1hr Temp Rise 1.5 °C 10:52 2.7 °C 3.4 °C, 2012 1.1 °C, 2018
Max 1hr Hum Rise 8% 17:42 9% 14%, 2017 5%, 2011
Max 10m Temp Fall 0.6 °C 17:02 0.5 °C 1.0 °C, 2012 0.4 °C, 2010
Max 1hr Temp Fall 2.1 °C 21:01 1.9 °C 2.6 °C, 2012 1.0 °C, 2013
Max 1hr Hum Fall 7% 11:13 11% 16%, 2014 6%, 2013
Max 10m Wind Speed 8.4 mph 23:33 7.0 mph 14.8 mph, 2011 3.7 mph, 2021
Minimum Feels-like 17.1 °C 23:53 20.1 °C 17.5 °C, 2022 6.1 °C, 2012
Maximum Feels-like 28.6 °C 13:21 34.2 °C 31.8 °C, 2022 18.3 °C, 2012
Mean Feels-like 24.2 °C 26.9 °C 25.0 °C, 2022 13.3 °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 9.0 °C (+1.3) 11.2 °C (+3.1) 14.4 °C (+6.7), 2016 5.7 °C (-2.0), 2013
Humidity Range 24% 36% 44%, 2011 23%, 2018
Pressure Range 4 hPa 4 hPa 12 hPa, 2017 2 hPa, 2021
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]85 hrs (138%) [59%] 10 [86%], 2009 0 [0%], 2023
Wet Hours 2
[Mean rain rate: 1.2 mm/h]
4 hrs (24%) [1.4%] 6, 2018 0, 2009
Cloud Cover unknown
Events None
Comments blr
Extra Comments
Issues None known
Observer Absent? No
Pond Temperature (Heath) 22.0 °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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