Daily Report for 18th January 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 2.5 °C (+0.1) 06:43 0.6 °C (-1.9) 7.6 °C (+5.2), 2014 -3.3 °C (-5.7), 2017
Maximum Temperature 8.6 °C (+1.6) 23:46 5.6 °C (-1.4) 11.9 °C (+4.9), 2012 1.8 °C (-5.2), 2013
Mean Temperature 5.2 °C (+0.8) 3.1 °C (-1.6) 9.3 °C, 2012 -0.8 °C, 2013
Minimum Humidity 83% 17:18 84% 95%, 2010 50%, 2009
Maximum Humidity 94% 08:31 94% 98%, 2010 82%, 2017
Mean Humidity 90% 90% 98%, 2010 70%, 2017
Minimum Pressure 1012 hPa 23:57 1017 hPa 1036 hPa, 2017 989 hPa, 2014
Maximum Pressure 1027 hPa 00:01 1024 hPa 1039 hPa, 2017 993 hPa, 2014
Mean Pressure 1022 hPa 1020 hPa 1038 hPa, 2017 990 hPa, 2014
Mean Wind Speed 5.5 mph (+0.3) 3.8 mph (-1.4) 10.4 mph, 2018 0.2 mph, 2017
Maximum Wind Speed 15.4 mph 23:57 11.2 mph 31.0 mph, 2018 3.8 mph, 2017
Maximum Gust 26.2 mph 19:00 17.7 mph 47.2 mph, 2018 5.2 mph, 2017
Mean Wind Direction WSW
Rainfall 0.0 mm 42.3 mm (132%) 7.6 mm, 2011
Maximum Hourly Rain n/a 3, 2009
Maximum 10-min Rain n/a 1.1, 2011
Maximum Rain Rate n/a 10, 2011
Minimum Dew Point 1.5 °C 06:37 -0.7 °C 4.8 °C, 2014 -6.8 °C, 2017
Maximum Dew Point 7.5 °C 23:48 4.0 °C 11.1 °C, 2012 -2.3 °C, 2013
Mean Dew Point 3.7 °C 1.7 °C 8.4 °C, 2012 -5.0 °C, 2017
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 2.5 °C 06:53 1.4 °C 6.8 °C, 2014 -3.3 °C, 2017
Day Maximum (09-21) * 8.0 °C * 20:54 5.2 °C 11.9 °C, 2012 -0.8 °C, 2013
Max 10m Temp Rise 0.3 °C 10:20 0.3 °C 0.9 °C, 2019 0.1 °C, 2013
Max 1hr Temp Rise 1.3 °C 11:08 1.0 °C 3.8 °C, 2019 0.4 °C, 2013
Max 1hr Hum Rise 4% 18:43 4% 6%, 2013 2%, 2010
Max 10m Temp Fall 0.2 °C 01:26 0.4 °C 0.4 °C, 2017 0.1 °C, 2012
Max 1hr Temp Fall 0.4 °C 04:34 1.1 °C 1.8 °C, 2018 0.3 °C, 2012
Max 1hr Hum Fall 4% 11:46 4% 15%, 2018 0%, 2010
Max 10m Wind Speed 12.3 mph 21:22 9.0 mph 23.3 mph, 2018 2.7 mph, 2017
Minimum Feels-like -1.4 °C 04:25 -3.7 °C 4.7 °C, 2014 -8.7 °C, 2013
Maximum Feels-like 6.5 °C 14:16 5.1 °C 13.7 °C, 2012 -0.4 °C, 2013
Mean Feels-like 2.6 °C 0.9 °C 8.9 °C, 2012 -5.3 °C, 2013
Air-frost Hrs 0 hrs 3 hrs 18 hrs, 2013 0 hrs, 2010
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 6.1 °C (+1.5) 5.0 °C (+0.4) 8.3 °C (+3.7), 2019 2.2 °C (-2.4), 2014
Humidity Range 11% 10% 44%, 2009 3%, 2010
Pressure Range 15 hPa 7 hPa 16 hPa, 2018 1 hPa, 2010
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0.2 [3%]22 hrs (65%) [17%] 7.6 [101%], 2020 0 [0%], 2012
Wet Hours 047 hrs (120%) [11%] 10, 2013 , 2009
Cloud Cover Hazy or Overcast
Events None
Comments -
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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Daily Graph of Conditions

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Webcam Summary of Cloud Conditions

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Wind rose