Daily Report for 9th January 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature -1.9 °C (-4.3) 23:55 -0.1 °C (-2.6) 8.4 °C (+6.0), 2015 -4.2 °C (-6.6), 2010
Maximum Temperature 2.8 °C (-4.2) 15:13 3.8 °C (-3.2) 14.8 °C (+7.8), 2015 0.6 °C (-6.4), 2010
Mean Temperature -0.1 °C (-4.3) 1.9 °C (-2.9) 11.9 °C, 2015 -1.9 °C, 2010
Minimum Humidity 83% 15:08 83% 88%, 2018 64%, 2014
Maximum Humidity 96% 03:29 94% 98%, 2013 84%, 2017
Mean Humidity 93% 90% 93%, 2021 78%, 2014
Minimum Pressure 1024 hPa 00:23 1018 hPa 1028 hPa, 2019 982 hPa, 2016
Maximum Pressure 1029 hPa 22:15 1021 hPa 1033 hPa, 2012 997 hPa, 2016
Mean Pressure 1027 hPa 1019 hPa 1030 hPa, 2012 989 hPa, 2016
Mean Wind Speed 1.0 mph (-4.2) 3.5 mph (-1.7) 11.1 mph, 2015 1.0 mph, 2021
Maximum Wind Speed 6.8 mph 00:49 9.8 mph 28.4 mph, 2015 6.8 mph, 2021
Maximum Gust 10.3 mph 00:08 15.2 mph 38.9 mph, 2016 10.3 mph, 2021
Mean Wind Direction NNE
Rainfall 0.0 mm 1.3 mm (8%) 6.4 mm, 2020
Maximum Hourly Rain n/a 4.4, 2020
Maximum 10-min Rain n/a 1.8, 2020
Maximum Rain Rate n/a 36, 2017
Minimum Dew Point -2.8 °C 19:12 -1.4 °C 6.1 °C, 2012 -5.4 °C, 2010
Maximum Dew Point 0.7 °C 14:14 2.0 °C 13.2 °C, 2015 -2.3 °C, 2010
Mean Dew Point -1.1 °C 0.4 °C 8.9 °C, 2020 -4.1 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * -0.9 °C * 08:45 0.7 °C 9.9 °C, 2020 -4.2 °C, 2010
Day Maximum (09-21) 2.8 °C 15:13 3.8 °C 14.8 °C, 2015 0.6 °C, 2010
Max 10m Temp Rise 0.5 °C 19:38 0.3 °C 0.8 °C, 2010 0.2 °C, 2012
Max 1hr Temp Rise 1.4 °C 13:41 0.9 °C 1.4 °C, 2011 0.4 °C, 2018
Max 1hr Hum Rise 4% 17:07 4% 13%, 2015 3%, 2012
Max 10m Temp Fall 0.4 °C 16:28 0.3 °C 1.2 °C, 2016 0.1 °C, 2018
Max 1hr Temp Fall 1.8 °C 17:01 1.0 °C 2.8 °C, 2016 0.2 °C, 2018
Max 1hr Hum Fall 6% 14:42 4% 15%, 2014 1%, 2018
Max 10m Wind Speed 4.9 mph 00:57 8.0 mph 20.4 mph, 2015 4.9 mph, 2021
Minimum Feels-like -5.8 °C 23:59 -4.7 °C 5.8 °C, 2012 -9.8 °C, 2010
Maximum Feels-like 2.8 °C 15:13 3.4 °C 17.4 °C, 2015 -3.3 °C, 2010
Mean Feels-like -1.0 °C -0.5 °C 12.2 °C, 2015 -6.7 °C, 2010
Air-frost Hrs 12 hrs 4 hrs 22 hrs, 2010 0 hrs, 2011
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 4.7 °C (+0.1) 3.9 °C (-0.7) 8.4 °C (+3.8), 2013 3.5 °C (-1.1), 2018
Humidity Range 13% 10% 32%, 2014 6%, 2017
Pressure Range 5 hPa 4 hPa 20 hPa, 2017 2 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 2 [28%]9 hrs (54%) [14%] 7.3 [101%], 2011 0 [0%], 2018
Wet Hours 05 hrs (26%) [2.3%] 8, 2017 , 2009
Cloud Cover unknown
Events Air Frost
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