Daily Report for 4th January 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 2.4 °C (-0.1) 23:11 0.5 °C (-2.0) 8.2 °C (+5.7), 2013 -4.2 °C (-6.7), 2010
Maximum Temperature 4.8 °C (-2.2) 12:53 4.6 °C (-2.4) 12.2 °C (+5.2), 2018 0.6 °C (-6.4), 2009
Mean Temperature 3.4 °C (-1.2) 2.7 °C (-2.2) 9.6 °C, 2013 -2.4 °C, 2010
Minimum Humidity 83% 16:01 84% 96%, 2015 51%, 2009
Maximum Humidity 90% 00:06 94% 98%, 2015 72%, 2009
Mean Humidity 87% 90% 97%, 2015 62%, 2009
Minimum Pressure 1019 hPa 13:24 1015 hPa 1041 hPa, 2019 982 hPa, 2016
Maximum Pressure 1021 hPa 21:20 1019 hPa 1044 hPa, 2019 984 hPa, 2016
Mean Pressure 1020 hPa 1017 hPa 1042 hPa, 2019 982 hPa, 2016
Mean Wind Speed 7.9 mph (+2.7) 4.0 mph (-1.2) 9.3 mph, 2012 1.8 mph, 2019
Maximum Wind Speed 14.8 mph 15:55 9.9 mph 28.6 mph, 2018 6.2 mph, 2010
Maximum Gust 22.8 mph 10:42 15.7 mph 42.6 mph, 2018 8.1 mph, 2010
Mean Wind Direction NE
Rainfall 0.0 mm 0.6 mm (8%) 10.3 mm, 2018
Maximum Hourly Rain n/a 3.1, 2018
Maximum 10-min Rain n/a 0.9, 2018
Maximum Rain Rate n/a 6.6, 2018
Minimum Dew Point 0.1 °C 23:00 -0.9 °C 5.8 °C, 2013 -5.4 °C, 2010
Maximum Dew Point 2.6 °C 11:43 2.9 °C 9.8 °C, 2018 -1.1 °C, 2010
Mean Dew Point 1.4 °C 1.1 °C 7.2 °C, 2013 -4.0 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 2.4 °C 04:11 1.1 °C 9.3 °C, 2013 -4.2 °C, 2010
Day Maximum (09-21) 4.8 °C 12:52 4.6 °C 12.2 °C, 2018 0.6 °C, 2009
Max 10m Temp Rise 0.3 °C 06:28 0.2 °C 0.7 °C, 2010 0.1 °C, 2013
Max 1hr Temp Rise 0.9 °C 07:11 0.9 °C 2.2 °C, 2010 0.4 °C, 2013
Max 1hr Hum Rise 6% 17:07 4% 7%, 2012 1%, 2015
Max 10m Temp Fall 0.3 °C 16:18 0.3 °C 0.8 °C, 2017 0.1 °C, 2020
Max 1hr Temp Fall 0.8 °C 16:41 0.9 °C 1.8 °C, 2017 0.3 °C, 2020
Max 1hr Hum Fall 4% 12:48 4% 14%, 2018 1%, 2015
Max 10m Wind Speed 13.9 mph 11:40 8.7 mph 20.9 mph, 2018 4.3 mph, 2010
Minimum Feels-like -3.1 °C 23:36 -4.3 °C 5.0 °C, 2013 -7.7 °C, 2010
Maximum Feels-like 3.2 °C 01:07 4.0 °C 12.7 °C, 2018 1.3 °C, 2010
Mean Feels-like -0.8 °C 0.1 °C 8.3 °C, 2013 -3.5 °C, 2010
Air-frost Hrs 0 hrs 1 hrs 20 hrs, 2010 0 hrs, 2011
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 2.4 °C (-2.1) 4.1 °C (-0.4) 6.3 °C (+1.8), 2018 2.4 °C (-2.1), 2011
Humidity Range 7% 9% 29%, 2018 2%, 2015
Pressure Range 2 hPa 4 hPa 18 hPa, 2012 2 hPa, 2013
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]3 hrs (41%) [11%] 7 [98%], 2010 0 [0%], 2014
Wet Hours 03 hrs (35%) [3.1%] 8, 2014 , 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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