Daily Report for 23rd January 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature -0.2 °C (-2.5) 23:54 1.4 °C (-1.0) 8.2 °C (+5.9), 2018 -4.1 °C (-6.4), 2015
Maximum Temperature 4.0 °C (-3.0) 00:00 6.2 °C (-0.9) 12.7 °C (+5.7), 2018 1.8 °C (-5.2), 2019
Mean Temperature 1.6 °C (-2.7) 3.8 °C (-0.9) 10.6 °C, 2018 0.1 °C, 2019
Minimum Humidity 79% 15:22 82% 88%, 2010 49%, 2009
Maximum Humidity 94% 10:25 94% 98%, 2010 83%, 2012
Mean Humidity 88% 89% 95%, 2010 71%, 2009
Minimum Pressure 995 hPa 06:18 1010 hPa 1033 hPa, 2011 967 hPa, 2009
Maximum Pressure 1000 hPa 22:59 1018 hPa 1037 hPa, 2020 985 hPa, 2009
Mean Pressure 996 hPa 1015 hPa 1034 hPa, 2011 976 hPa, 2009
Mean Wind Speed 3.1 mph (-2.1) 4.7 mph (-0.5) 8.1 mph, 2018 0.2 mph, 2017
Maximum Wind Speed 11.7 mph 13:58 12.6 mph 16.8 mph, 2018 3.7 mph, 2017
Maximum Gust 16.0 mph 13:59 19.9 mph 30.0 mph, 2018 4.2 mph, 2017
Mean Wind Direction NW
Rainfall 0.2 mm 48.7 mm (119%) 11.0 mm, 2009
Maximum Hourly Rain 0.2 mm 5.0 mm, 2009
Maximum 10-min Rain 0.2 mm 0.9 mm, 2014
Maximum Rain Rate n/a 6, 2014
Minimum Dew Point -1.7 °C 21:56 -0.0 °C 5.0 °C, 2018 -5.6 °C, 2015
Maximum Dew Point 2.2 °C 00:00 4.4 °C 11.1 °C, 2018 -0.5 °C, 2013
Mean Dew Point -0.1 °C 2.2 °C 8.5 °C, 2018 -1.3 °C, 2013
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 0.2 °C * 08:04 2.1 °C 7.7 °C, 2018 -4.1 °C, 2015
Day Maximum (09-21) * 3.6 °C * 14:21 5.9 °C 12.7 °C, 2018 1.8 °C, 2019
Max 10m Temp Rise 0.4 °C 13:08 0.3 °C 0.5 °C, 2015 0.1 °C, 2010
Max 1hr Temp Rise 1.6 °C 13:39 1.0 °C 2.0 °C, 2015 0.1 °C, 2010
Max 1hr Hum Rise 4% 16:22 4% 7%, 2018 2%, 2010
Max 10m Temp Fall 0.4 °C 01:39 0.4 °C 0.4 °C, 2016 0.1 °C, 2011
Max 1hr Temp Fall 1.3 °C 01:39 1.2 °C 1.7 °C, 2019 0.3 °C, 2020
Max 1hr Hum Fall 10% 14:08 5% 21%, 2014 2%, 2017
Max 10m Wind Speed 8.7 mph 13:59 9.9 mph 12.7 mph, 2018 2.2 mph, 2017
Minimum Feels-like -3.9 °C 20:19 -2.9 °C 4.9 °C, 2018 -6.2 °C, 2015
Maximum Feels-like 3.8 °C 00:18 5.8 °C 14.3 °C, 2018 1.7 °C, 2019
Mean Feels-like -0.5 °C 1.7 °C 10.2 °C, 2018 -2.3 °C, 2013
Air-frost Hrs 2 hrs 2 hrs 11 hrs, 2015 0 hrs, 2010
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 4.2 °C (-0.5) 4.8 °C (+0.2) 11.4 °C (+6.7), 2015 1.4 °C (-3.3), 2013
Humidity Range 15% 11% 44%, 2009 5%, 2017
Pressure Range 5 hPa 8 hPa 18 hPa, 2009 2 hPa, 2011
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 2 [26%]33 hrs (75%) [19%] 6 [77%], 2015 0 [0%], 2011
Wet Hours 155 hrs (110%) [9.9%] 2, 2015 , 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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Wind rose