Daily Report for 18th February 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 5.6 °C (+3.6) 23:49 1.8 °C (-0.3) 6.2 °C (+4.2), 2009 -0.8 °C (-2.8), 2010
Maximum Temperature 10.8 °C (+3.3) 09:23 6.0 °C (-1.3) 11.3 °C (+3.8), 2017 4.8 °C (-2.7), 2010
Mean Temperature 8.5 °C (+3.5) 4.2 °C (-0.8) 8.5 °C, 2021 2.1 °C, 2010
Minimum Humidity 65% 15:53 75% 88%, 2010 51%, 2016
Maximum Humidity 89% 10:42 91% 98%, 2010 81%, 2015
Mean Humidity 80% 84% 96%, 2010 71%, 2015
Minimum Pressure 999 hPa 09:47 1009 hPa 1031 hPa, 2015 986 hPa, 2010
Maximum Pressure 1011 hPa 23:55 1016 hPa 1042 hPa, 2015 992 hPa, 2010
Mean Pressure 1005 hPa 1012 hPa 1036 hPa, 2015 989 hPa, 2010
Mean Wind Speed 8.0 mph (+2.9) 5.9 mph (+0.8) 8.1 mph, 2020 2.6 mph, 2010
Maximum Wind Speed 16.2 mph 04:24 14.1 mph 20.4 mph, 2012 8.8 mph, 2017
Maximum Gust 26.2 mph 09:27 22.0 mph 34.6 mph, 2020 10.9 mph, 2010
Mean Wind Direction SW
Rainfall 1.4 mm 39.7 mm (151%) 9.0 mm, 2010
Maximum Hourly Rain 1.4 mm 10:45 4.3 mm, 2014
Maximum 10-min Rain 1.0 mm 10:30 2.1 mm, 2014
Maximum Rain Rate 7 mm/h 10:23 60 mm/h, 2014
Minimum Dew Point 2.3 °C 18:15 -0.6 °C 4.8 °C, 2014 -4.9 °C, 2016
Maximum Dew Point 8.3 °C 10:27 3.4 °C 8.5 °C, 2014 2.2 °C, 2015
Mean Dew Point 5.1 °C 1.6 °C 6.8 °C, 2014 -0.1 °C, 2016
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 8.6 °C * 01:52 2.5 °C 8.7 °C, 2019 -0.8 °C, 2010
Day Maximum (09-21) 10.8 °C 09:25 5.8 °C 11.3 °C, 2017 4.8 °C, 2010
Max 10m Temp Rise 0.3 °C 08:05 0.3 °C 1.3 °C, 2009 0.2 °C, 2017
Max 1hr Temp Rise 1.1 °C 08:46 1.1 °C 3.7 °C, 2018 0.5 °C, 2019
Max 1hr Hum Rise 8% 10:36 6% 14%, 2012 2%, 2010
Max 10m Temp Fall 0.3 °C 16:27 0.3 °C 1.7 °C, 2012 0.2 °C, 2010
Max 1hr Temp Fall 1.4 °C 17:19 0.9 °C 3.6 °C, 2012 0.7 °C, 2010
Max 1hr Hum Fall 9% 14:01 7% 13%, 2016 1%, 2010
Max 10m Wind Speed 13.1 mph 09:28 11.1 mph 14.5 mph, 2020 5.7 mph, 2010
Minimum Feels-like 1.8 °C 22:18 -3.3 °C 2.9 °C, 2017 -3.6 °C, 2010
Maximum Feels-like 11.2 °C 10:02 5.3 °C 11.3 °C, 2017 4.8 °C, 2010
Mean Feels-like 5.8 °C 1.2 °C 6.9 °C, 2014 1.1 °C, 2010
Air-frost Hrs 0 hrs 7 hrs 8 hrs, 2010 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 5.2 °C (-0.3) 4.2 °C (-1.0) 8.4 °C (+2.9), 2018 3.3 °C (-2.2), 2009
Humidity Range 24% 16% 41%, 2016 8%, 2019
Pressure Range 11 hPa 7 hPa 12 hPa, 2012 1 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 3 [33%]23 hrs (49%) [15%] 9 [99%], 2015 0 [0%], 2019
Wet Hours 2
[Mean rain rate: 0.7 mm/h]
54 hrs (162%) [13%] 6, 2010 , 2009
Cloud Cover unknown
Events None
Comments blr
Extra Comments
Issues None known
Observer Absent? No
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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