Daily Report for 14th January 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 1.4 °C (-1.0) 23:55 0.3 °C (-2.2) 7.8 °C (+5.4), 2011 -2.9 °C (-5.3), 2012
Maximum Temperature 9.3 °C (+2.3) 00:46 5.3 °C (-1.7) 12.9 °C (+5.9), 2020 2.4 °C (-4.6), 2013
Mean Temperature 4.0 °C (+0.6) 2.9 °C (-1.9) 10.5 °C, 2011 0.7 °C, 2012
Minimum Humidity 91% 01:38 85% 98%, 2010 58%, 2015
Maximum Humidity 96% 08:28 94% 98%, 2010 81%, 2019
Mean Humidity 95% 91% 98%, 2010 74%, 2015
Minimum Pressure 1014 hPa 08:02 1017 hPa 1027 hPa, 2012 992 hPa, 2015
Maximum Pressure 1026 hPa 23:57 1022 hPa 1032 hPa, 2012 1000 hPa, 2020
Mean Pressure 1018 hPa 1019 hPa 1030 hPa, 2012 997 hPa, 2020
Mean Wind Speed 4.1 mph (-1.1) 3.6 mph (-1.6) 11.5 mph, 2020 0.8 mph, 2012
Maximum Wind Speed 12.8 mph 10:18 10.5 mph 27.9 mph, 2020 5.9 mph, 2012
Maximum Gust 24.0 mph 10:18 16.9 mph 42.6 mph, 2020 7.4 mph, 2012
Mean Wind Direction E
Rainfall 25.2 mm 37.0 mm (149%) 25.2 mm, 2021
Maximum Hourly Rain 4.3 mm 02:21 5.5 mm, 2011
Maximum 10-min Rain 1.5 mm 02:17 3.8 mm, 2011
Maximum Rain Rate 14 mm/h 02:12 40 mm/h, 2011
Minimum Dew Point 0.2 °C 23:55 -1.0 °C 6.7 °C, 2011 -4.8 °C, 2016
Maximum Dew Point 8.5 °C 00:46 3.7 °C 11.5 °C, 2020 0.5 °C, 2017
Mean Dew Point 3.2 °C 1.5 °C 9.3 °C, 2011 -1.7 °C, 2017
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 4.4 °C * 03:35 1.4 °C 11.3 °C, 2011 -2.9 °C, 2012
Day Maximum (09-21) * 4.7 °C * 09:35 4.9 °C 12.9 °C, 2020 2.4 °C, 2013
Max 10m Temp Rise 0.2 °C 19:50 0.3 °C 0.5 °C, 2012 0.1 °C, 2011
Max 1hr Temp Rise 0.2 °C 05:04 0.9 °C 1.9 °C, 2012 0.2 °C, 2021
Max 1hr Hum Rise 3% 02:38 4% 14%, 2015 0%, 2010
Max 10m Temp Fall 1.5 °C 01:24 0.4 °C 1.5 °C, 2021 0.2 °C, 2010
Max 1hr Temp Fall 3.9 °C 02:10 1.2 °C 3.9 °C, 2021 0.5 °C, 2010
Max 1hr Hum Fall 4% 01:38 4% 13%, 2014 0%, 2010
Max 10m Wind Speed 10.6 mph 10:21 8.5 mph 20.9 mph, 2020 3.8 mph, 2010
Minimum Feels-like -3.8 °C 23:43 -4.0 °C 5.3 °C, 2011 -6.2 °C, 2017
Maximum Feels-like 9.9 °C 00:00 4.9 °C 14.9 °C, 2020 1.6 °C, 2013
Mean Feels-like 1.4 °C 0.7 °C 10.9 °C, 2011 -1.4 °C, 2013
Air-frost Hrs 0 hrs 4 hrs 10 hrs, 2012 0 hrs, 2010
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 7.9 °C (+3.3) 5.0 °C (+0.5) 7.9 °C (+3.3), 2012 2.3 °C (-2.3), 2009
Humidity Range 5% 10% 31%, 2015 0%, 2010
Pressure Range 12 hPa 6 hPa 17 hPa, 2013 4 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]18 hrs (67%) [17%] 7.4 [100%], 2012 0 [0%], 2009
Wet Hours 14
[Mean rain rate: 1.8 mm/h]
40 hrs (132%) [12%] 14, 2021 , 2009
Cloud Cover Overcast
Events None
Comments rn
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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Webcam Summary of Cloud Conditions

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