Daily Report for 18th March 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 3.9 °C (+0.1) 01:57 3.7 °C (+0.5) 10.4 °C (+6.6), 2017 -1.7 °C (-5.5), 2018
Maximum Temperature 8.9 °C (-1.6) 21:09 9.0 °C (-0.7) 17.4 °C (+6.9), 2010 0.3 °C (-10.2), 2018
Mean Temperature 7.0 °C (-0.8) 6.3 °C (-0.1) 12.6 °C, 2017 -0.6 °C, 2018
Minimum Humidity 77% 11:51 67% 81%, 2013 39%, 2010
Maximum Humidity 93% 21:46 90% 98%, 2013 81%, 2014
Mean Humidity 86% 80% 93%, 2013 67%, 2014
Minimum Pressure 1025 hPa 23:30 1017 hPa 1028 hPa, 2009 989 hPa, 2013
Maximum Pressure 1034 hPa 00:09 1026 hPa 1036 hPa, 2009 994 hPa, 2013
Mean Pressure 1029 hPa 1022 hPa 1032 hPa, 2009 991 hPa, 2013
Mean Wind Speed 4.4 mph (-0.8) 5.5 mph (+0.3) 9.8 mph, 2018 1.2 mph, 2013
Maximum Wind Speed 15.7 mph 22:08 14.1 mph 18.8 mph, 2018 6.7 mph, 2013
Maximum Gust 25.1 mph 22:24 21.2 mph 31.1 mph, 2018 8.7 mph, 2013
Mean Wind Direction N
Rainfall 0.2 mm 17.7 mm (73%) 11.5 mm, 2013
Maximum Hourly Rain 0.2 mm 3.4 mm, 2013
Maximum 10-min Rain 0.2 mm 1.2 mm, 2013
Maximum Rain Rate n/a 17, 2013
Minimum Dew Point 2.4 °C 01:57 0.9 °C 6.5 °C, 2017 -4.7 °C, 2018
Maximum Dew Point 7.8 °C 21:45 5.3 °C 10.8 °C, 2017 -2.4 °C, 2018
Mean Dew Point 4.8 °C 3.0 °C 9.1 °C, 2017 -3.4 °C, 2018
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 3.9 °C 01:55 3.9 °C 9.9 °C, 2017 -1.7 °C, 2018
Day Maximum (09-21) * 8.8 °C * 20:38 9.0 °C 17.4 °C, 2010 -0.1 °C, 2018
Max 10m Temp Rise 0.3 °C 07:06 0.4 °C 0.8 °C, 2010 0.2 °C, 2011
Max 1hr Temp Rise 1.0 °C 07:38 1.4 °C 3.3 °C, 2010 0.5 °C, 2011
Max 1hr Hum Rise 5% 16:19 7% 16%, 2010 3%, 2017
Max 10m Temp Fall 0.3 °C 13:19 0.6 °C 0.7 °C, 2020 0.2 °C, 2017
Max 1hr Temp Fall 0.8 °C 22:49 1.4 °C 2.4 °C, 2020 0.7 °C, 2017
Max 1hr Hum Fall 5% 11:47 8% 23%, 2010 4%, 2016
Max 10m Wind Speed 10.9 mph 22:17 10.6 mph 14.3 mph, 2018 5.6 mph, 2013
Minimum Feels-like 0.5 °C 02:47 0.1 °C 10.4 °C, 2017 -8.7 °C, 2018
Maximum Feels-like 8.7 °C 15:03 9.0 °C 17.4 °C, 2010 -2.4 °C, 2018
Mean Feels-like 4.8 °C 4.4 °C 13.5 °C, 2017 -6.5 °C, 2018
Air-frost Hrs 0 hrs 0.2 hrs 19 hrs, 2018 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 5.0 °C (-1.7) 5.3 °C (-1.2) 12.6 °C (+5.9), 2009 2.0 °C (-4.7), 2018
Humidity Range 16% 22% 53%, 2009 14%, 2017
Pressure Range 9 hPa 9 hPa 17 hPa, 2012 3 hPa, 2020
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]39 hrs (66%) [21%] 11.5 [107%], 2009 0 [0%], 2016
Wet Hours 123 hrs (75%) [5.3%] 6, 2013 , 2009
Cloud Cover Overcast
Events None
Comments some rn/dz
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