Daily Report for 24th January 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature -2.2 °C (-4.5) 05:13 1.2 °C (-1.2) 9.3 °C (+7.0), 2016 -2.3 °C (-4.6), 2019
Maximum Temperature 1.1 °C (-5.9) 15:15 5.9 °C (-1.1) 14.8 °C (+7.8), 2016 1.1 °C (-5.9), 2021
Mean Temperature 0.0 °C (-5.2) 3.7 °C (-1.1) 12.4 °C, 2016 0.0 °C, 2021
Minimum Humidity 87% 10:21 82% 90%, 2019 61%, 2015
Maximum Humidity 94% 14:39 94% 97%, 2012 86%, 2017
Mean Humidity 92% 90% 93%, 2012 76%, 2009
Minimum Pressure 995 hPa 13:43 1010 hPa 1026 hPa, 2017 984 hPa, 2009
Maximum Pressure 1001 hPa 23:47 1018 hPa 1034 hPa, 2011 995 hPa, 2009
Mean Pressure 998 hPa 1014 hPa 1029 hPa, 2011 990 hPa, 2009
Mean Wind Speed 1.6 mph (-3.6) 4.6 mph (-0.6) 10.6 mph, 2018 0.6 mph, 2017
Maximum Wind Speed 8.3 mph 12:35 12.4 mph 24.9 mph, 2018 6.1 mph, 2017
Maximum Gust 13.7 mph 12:12 19.7 mph 46.1 mph, 2018 7.3 mph, 2017
Mean Wind Direction ENE
Rainfall / Snow-melt approx. 4.0 mm 52.7 mm (124%) 11.4 mm, 2018
Maximum Hourly Rain 1.0 mm 12:00 5.7 mm, 2018
Maximum 10-min Rain 0.3 mm 11:30 2.6 mm, 2018
Maximum Rain Rate 5.0 mm/h 11:30 53 mm/h, 2018
Minimum Dew Point -3.5 °C 05:10 -0.2 °C 8.0 °C, 2016 -4.8 °C, 2013
Maximum Dew Point 0.2 °C 15:08 4.3 °C 13.2 °C, 2016 -0.9 °C, 2013
Mean Dew Point -1.1 °C 2.1 °C 11.7 °C, 2016 -2.2 °C, 2013
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) -2.2 °C 05:18 1.9 °C 10.8 °C, 2018 -2.3 °C, 2019
Day Maximum (09-21) 1.1 °C 15:12 5.7 °C 12.8 °C, 2018 1.1 °C, 2021
Max 10m Temp Rise 0.4 °C 07:49 0.3 °C 0.5 °C, 2017 0.1 °C, 2013
Max 1hr Temp Rise 1.1 °C 08:40 1.0 °C 1.8 °C, 2017 0.3 °C, 2013
Max 1hr Hum Rise 5% 11:12 4% 8%, 2018 1%, 2020
Max 10m Temp Fall 0.2 °C 05:00 0.4 °C 1.8 °C, 2018 0.2 °C, 2010
Max 1hr Temp Fall 0.7 °C 05:07 1.2 °C 3.6 °C, 2018 0.3 °C, 2020
Max 1hr Hum Fall 3% 08:43 5% 11%, 2016 1%, 2012
Max 10m Wind Speed 6.3 mph 20:57 9.7 mph 20.0 mph, 2018 4.0 mph, 2020
Minimum Feels-like -4.9 °C 09:12 -3.0 °C 8.0 °C, 2016 -5.9 °C, 2019
Maximum Feels-like 1.1 °C 14:15 5.6 °C 14.6 °C, 2018 1.1 °C, 2021
Mean Feels-like -1.3 °C 1.6 °C 15.2 °C, 2016 -1.3 °C, 2021
Air-frost Hrs 10 hrs 3 hrs 10 hrs, 2021 0 hrs, 2010
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 3.3 °C (-1.4) 4.7 °C (+0.1) 7.8 °C (+3.1), 2012 1.6 °C (-3.1), 2020
Humidity Range 7% 11% 35%, 2015 3%, 2016
Pressure Range 6 hPa 8 hPa 16 hPa, 2015 2 hPa, 2016
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]33 hrs (72%) [18%] 7.7 [99%], 2015 0 [0%], 2010
Wet Hours 4
[Mean rain rate: 1.0 mm/h]
59 hrs (113%) [10%] 8, 2012 , 2009
Cloud Cover Overcast
Events Snowfall: ~4 cm
Air Frost
Comments 10-12 Snow; eve sn/rn
Extra Comments Lying snow at midday of ~3cm
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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Daily Graph of Conditions

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Webcam Summary of Cloud Conditions

daycamsumFull resolution individual images at up-to 5 minute intervals

Wind rose