Daily Report for 17th February 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 7.8 °C (+5.9) 01:02 1.6 °C (-0.5) 7.8 °C (+5.9), 2021 -0.3 °C (-2.2), 2010
Maximum Temperature 10.9 °C (+3.5) 13:28 5.7 °C (-1.5) 14.1 °C (+6.7), 2019 7.0 °C (-0.4), 2016
Mean Temperature 9.7 °C (+4.7) 3.9 °C (-1.0) 9.7 °C, 2019 3.5 °C, 2010
Minimum Humidity 82% 21:53 75% 82%, 2021 47%, 2015
Maximum Humidity 92% 15:45 91% 98%, 2010 82%, 2020
Mean Humidity 88% 84% 89%, 2011 72%, 2016
Minimum Pressure 1008 hPa 23:56 1010 hPa 1025 hPa, 2017 989 hPa, 2010
Maximum Pressure 1012 hPa 00:49 1016 hPa 1041 hPa, 2015 992 hPa, 2010
Mean Pressure 1011 hPa 1013 hPa 1035 hPa, 2015 990 hPa, 2010
Mean Wind Speed 9.1 mph (+4.0) 5.8 mph (+0.7) 10.2 mph, 2020 1.8 mph, 2017
Maximum Wind Speed 17.8 mph 19:40 13.9 mph 19.8 mph, 2020 6.4 mph, 2017
Maximum Gust 26.2 mph 20:18 21.7 mph 39.2 mph, 2020 9.4 mph, 2017
Mean Wind Direction SW
Rainfall 1.0 mm 38.3 mm (154%) 7.0 mm, 2016
Maximum Hourly Rain 1.0 mm 15:23 2.3 mm, 2016
Maximum 10-min Rain 0.5 mm 15:23 0.6 mm, 2016
Maximum Rain Rate 2.1 mm/h 15:23 8 mm/h, 2016
Minimum Dew Point 6.3 °C 01:05 -0.8 °C 6.3 °C, 2021 -3.5 °C, 2015
Maximum Dew Point 9.2 °C 14:23 3.1 °C 9.2 °C, 2019 2.5 °C, 2015
Mean Dew Point 7.8 °C 1.3 °C 7.8 °C, 2021 -0.2 °C, 2015
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 7.8 °C 00:59 2.2 °C 7.9 °C, 2017 0.4 °C, 2013
Day Maximum (09-21) 10.9 °C 13:31 5.5 °C 14.1 °C, 2019 7.0 °C, 2016
Max 10m Temp Rise 0.2 °C 03:50 0.4 °C 0.7 °C, 2019 0.2 °C, 2021
Max 1hr Temp Rise 0.7 °C 04:39 1.1 °C 2.7 °C, 2018 0.7 °C, 2021
Max 1hr Hum Rise 3% 14:23 6% 13%, 2013 3%, 2011
Max 10m Temp Fall 0.3 °C 14:38 0.3 °C 0.5 °C, 2015 0.2 °C, 2011
Max 1hr Temp Fall 0.7 °C 23:20 0.9 °C 2.3 °C, 2015 0.7 °C, 2009
Max 1hr Hum Fall 4% 20:44 6% 21%, 2013 4%, 2009
Max 10m Wind Speed 13.8 mph 19:34 11.0 mph 16.1 mph, 2020 4.1 mph, 2017
Minimum Feels-like 4.4 °C 01:11 -3.6 °C 5.7 °C, 2017 -2.6 °C, 2015
Maximum Feels-like 11.7 °C 13:34 5.0 °C 14.9 °C, 2019 5.2 °C, 2016
Mean Feels-like 8.6 °C 1.0 °C 9.5 °C, 2019 1.8 °C, 2016
Air-frost Hrs 0 hrs 7 hrs 0.4 hrs, 2010 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 3.1 °C (-2.4) 4.1 °C (-1.0) 9.9 °C (+4.4), 2019 3.1 °C (-2.4), 2021
Humidity Range 10% 16% 43%, 2013 10%, 2021
Pressure Range 4 hPa 6 hPa 18 hPa, 2015 2 hPa, 2018
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]20 hrs (45%) [14%] 9 [100%], 2015 0 [0%], 2021
Wet Hours 2
[Mean rain rate: 0.5 mm/h]
52 hrs (165%) [13%] 7, 2016 , 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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Webcam Summary of Cloud Conditions

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