Daily Report for 25th November 2020

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 5.8 °C (+1.9) 23:59 6.9 °C (+1.7) 9.4 °C (+5.5), 2019 -0.4 °C (-4.3), 2010
Maximum Temperature 13.2 °C (+3.8) 13:46 12.8 °C (+2.6) 13.4 °C (+4.0), 2009 2.1 °C (-7.3), 2010
Mean Temperature 9.9 °C (+2.9) 10.1 °C (+2.2) 10.7 °C, 2011 1.1 °C, 2010
Minimum Humidity 85% 19:42 76% 88%, 2014 55%, 2016
Maximum Humidity 91% 08:45 94% 98%, 2012 80%, 2016
Mean Humidity 88% 87% 96%, 2014 71%, 2016
Minimum Pressure 1011 hPa 04:38 1015 hPa 1034 hPa, 2013 989 hPa, 2012
Maximum Pressure 1021 hPa 23:36 1025 hPa 1038 hPa, 2013 1002 hPa, 2009
Mean Pressure 1014 hPa 1020 hPa 1036 hPa, 2013 998 hPa, 2009
Mean Wind Speed 4.0 mph (-0.6) 5.0 mph (+0.4) 9.8 mph, 2012 3.7 mph, 2014
Maximum Wind Speed 10.0 mph 13:18 12.7 mph 24.6 mph, 2012 9.7 mph, 2013
Maximum Gust 14.8 mph 09:35 20.6 mph 37.5 mph, 2012 13.5 mph, 2014
Mean Wind Direction WSW
Rainfall 0.0 mm 32.2 mm (64%) 3.8 mm, 2009
Maximum Hourly Rain n/a 2.2, 2009
Maximum 10-min Rain n/a 0.5, 2012
Maximum Rain Rate n/a 2.8, 2012
Minimum Dew Point 4.1 °C 23:59 5.1 °C 7.5 °C, 2019 -3.0 °C, 2010
Maximum Dew Point 11.3 °C 13:39 10.5 °C 11.7 °C, 2012 -0.8 °C, 2010
Mean Dew Point 8.1 °C 7.9 °C 9.4 °C, 2019 -1.9 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 9.1 °C * 23:29 8.2 °C 10.3 °C, 2011 -0.3 °C, 2017
Day Maximum (09-21) 13.2 °C 13:47 12.6 °C 13.2 °C, 2020 2.1 °C, 2010
Max 10m Temp Rise 0.3 °C 00:34 0.4 °C 0.9 °C, 2009 0.2 °C, 2010
Max 1hr Temp Rise 0.7 °C 01:05 1.4 °C 1.7 °C, 2014 0.4 °C, 2019
Max 1hr Hum Rise 2% 05:17 6% 26%, 2009 2%, 2019
Max 10m Temp Fall 0.5 °C 14:35 0.5 °C 1.6 °C, 2009 0.1 °C, 2014
Max 1hr Temp Fall 2.5 °C 15:29 1.3 °C 3.0 °C, 2009 0.4 °C, 2014
Max 1hr Hum Fall 3% 13:16 7% 19%, 2009 2%, 2019
Max 10m Wind Speed 8.1 mph 12:09 8.5 mph 18.7 mph, 2012 7.3 mph, 2013
Minimum Feels-like 5.6 °C 20:47 5.8 °C 6.5 °C, 2019 -4.4 °C, 2010
Maximum Feels-like 15.1 °C 13:38 14.3 °C 15.1 °C, 2020 2.1 °C, 2010
Mean Feels-like 9.8 °C 10.5 °C 11.1 °C, 2019 -1.4 °C, 2010
Air-frost Hrs 0 hrs 0 hrs 0.8 hrs, 2010 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 7.4 °C (+1.8) 5.9 °C (+0.8) 7.4 °C (+1.8), 2020 2.0 °C (-3.5), 2019
Humidity Range 6% 17% 34%, 2011 6%, 2019
Pressure Range 10 hPa 10 hPa 18 hPa, 2012 2 hPa, 2010
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0.1 [1%]62 hrs (99%) [31%] 7.5 [100%], 2016 0 [0%], 2019
Wet Hours 044 hrs (83%) [7.3%] 3, 2009 0, 2010
Cloud Cover am: Overcast
pm: Overcast or Mostly Cloudy
Events None
Comments -
Extra Comments
Issues wind from harpenden
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 10.5 °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