Daily Report for 12th March 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 4.7 °C (+1.4) 02:30 2.9 °C (-0.1) 9.3 °C (+6.0), 2017 -2.2 °C (-5.5), 2013
Maximum Temperature 10.6 °C (+0.7) 15:15 8.3 °C (-1.1) 14.9 °C (+5.0), 2014 3.9 °C (-6.0), 2013
Mean Temperature 7.5 °C (+1.0) 5.6 °C (-0.6) 11.2 °C, 2017 0.7 °C, 2013
Minimum Humidity 56% 15:07 67% 87%, 2018 28%, 2015
Maximum Humidity 88% 23:36 90% 96%, 2012 76%, 2015
Mean Humidity 77% 80% 92%, 2018 50%, 2015
Minimum Pressure 994 hPa 23:58 1018 hPa 1034 hPa, 2012 986 hPa, 2018
Maximum Pressure 1007 hPa 01:22 1026 hPa 1036 hPa, 2012 1000 hPa, 2018
Mean Pressure 1002 hPa 1022 hPa 1035 hPa, 2012 990 hPa, 2018
Mean Wind Speed 10.4 mph (+5.2) 5.0 mph (-0.2) 11.4 mph, 2020 1.5 mph, 2017
Maximum Wind Speed 19.2 mph 14:58 13.2 mph 25.6 mph, 2013 6.4 mph, 2014
Maximum Gust 20.8 mph 12:06 19.3 mph 39.3 mph, 2013 8.7 mph, 2014
Mean Wind Direction W
Rainfall 1.4 mm 12.6 mm (78%) 7.7 mm, 2019
Maximum Hourly Rain 0.8 mm 09:50 4.2 mm, 2019
Maximum 10-min Rain 0.5 mm 09:00 2.6 mm, 2019
Maximum Rain Rate 1.8 mm/h 09:00 53 mm/h, 2019
Minimum Dew Point 2.0 °C 01:39 0.2 °C 6.7 °C, 2009 -10.3 °C, 2013
Maximum Dew Point 5.1 °C 21:49 4.3 °C 9.4 °C, 2017 -0.9 °C, 2013
Mean Dew Point 3.6 °C 2.3 °C 8.1 °C, 2009 -6.7 °C, 2013
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 4.7 °C 02:31 3.2 °C 9.3 °C, 2017 -2.2 °C, 2013
Day Maximum (09-21) 10.6 °C 15:16 8.2 °C 14.9 °C, 2014 3.9 °C, 2013
Max 10m Temp Rise 0.3 °C 08:09 0.4 °C 0.8 °C, 2020 0.3 °C, 2019
Max 1hr Temp Rise 1.2 °C 08:14 1.2 °C 2.8 °C, 2020 0.8 °C, 2019
Max 1hr Hum Rise 10% 18:59 7% 17%, 2020 3%, 2018
Max 10m Temp Fall 0.4 °C 16:38 0.4 °C 1.8 °C, 2019 0.2 °C, 2017
Max 1hr Temp Fall 1.1 °C 16:48 1.2 °C 4.1 °C, 2019 0.8 °C, 2017
Max 1hr Hum Fall 12% 12:17 8% 19%, 2020 6%, 2010
Max 10m Wind Speed 14.7 mph 15:03 9.7 mph 20.6 mph, 2013 3.8 mph, 2016
Minimum Feels-like 0.2 °C 03:42 -0.5 °C 9.0 °C, 2017 -10.8 °C, 2013
Maximum Feels-like 10.6 °C 15:04 8.3 °C 14.9 °C, 2014 1.7 °C, 2013
Mean Feels-like 4.7 °C 3.9 °C 11.5 °C, 2017 -4.7 °C, 2013
Air-frost Hrs 0 hrs 0.3 hrs 9 hrs, 2013 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 5.9 °C (-0.8) 5.5 °C (-1.1) 11.9 °C (+5.2), 2014 3.1 °C (-3.6), 2017
Humidity Range 32% 23% 48%, 2015 9%, 2018
Pressure Range 13 hPa 8 hPa 22 hPa, 2019 2 hPa, 2012
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 2.5 [24%]31 hrs (78%) [25%] 10 [96%], 2012 0 [0%], 2009
Wet Hours 3
[Mean rain rate: 0.5 mm/h]
16 hrs (78%) [5.6%] 7, 2019 , 2009
Cloud Cover am: Overcast
pm: Partly Cloudy
Events None
Comments rn spells
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 4.5 °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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Wind rose