Daily Report for 11th December 2020

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 6.7 °C (+3.0) 19:50 2.8 °C (-1.0) 6.7 °C (+3.0), 2020 -3.9 °C (-7.6), 2022
Maximum Temperature 10.8 °C (+2.5) 14:31 6.4 °C (-2.3) 10.8 °C (+2.5), 2020 -0.1 °C (-8.4), 2022
Mean Temperature 8.8 °C (+2.8) 4.7 °C (-1.6) 9.1 °C, 2015 -1.9 °C, 2022
Minimum Humidity 90% 16:45 85% 96%, 2009 65%, 2014
Maximum Humidity 96% 20:14 94% 98%, 2009 79%, 2016
Mean Humidity 94% 89% 98%, 2009 77%, 2014
Minimum Pressure 986 hPa 13:49 995 hPa 1032 hPa, 2024 978 hPa, 2017
Maximum Pressure 993 hPa 00:01 1006 hPa 1034 hPa, 2009 993 hPa, 2020
Mean Pressure 988 hPa 1001 hPa 1033 hPa, 2024 985 hPa, 2017
Mean Wind Speed 2.1 mph (-3.0) 2.8 mph (-2.3) 8.7 mph, 2014 0.6 mph, 2013
Maximum Wind Speed 9.2 mph 00:01 9.1 mph 18.7 mph, 2023 4.0 mph, 2013
Maximum Gust 16.0 mph 02:47 14.4 mph 32.3 mph, 2023 5.9 mph, 2013
Mean Wind Direction SW
Rainfall 7.6 mm 33.1 mm (164%) 16.1 mm, 2017
Maximum Hourly Rain 3.3 mm 01:48 5.3 mm, 2011
Maximum 10-min Rain 0.7 mm 01:22 2.0 mm, 2011
Maximum Rain Rate 18 mm/h 00:54 24 mm/h, 2015
Minimum Dew Point 5.7 °C 19:43 1.3 °C 5.7 °C, 2020 -4.6 °C, 2022
Maximum Dew Point 9.5 °C 13:48 4.7 °C 9.9 °C, 2021 -0.5 °C, 2022
Mean Dew Point 7.9 °C 3.1 °C 7.9 °C, 2020 -2.4 °C, 2022
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 7.3 °C * 21:29 3.2 °C 9.5 °C, 2015 -3.9 °C, 2022
Day Maximum (09-21) 10.8 °C 14:25 6.3 °C 10.8 °C, 2020 -0.1 °C, 2022
Max 10m Temp Rise 0.4 °C 20:05 0.3 °C 0.6 °C, 2009 0.1 °C, 2015
Max 1hr Temp Rise 1.0 °C 20:50 1.0 °C 2.1 °C, 2018 0.4 °C, 2015
Max 1hr Hum Rise 4% 20:20 3% 9%, 2014 1%, 2009
Max 10m Temp Fall 0.4 °C 16:46 0.3 °C 0.6 °C, 2014 0.1 °C, 2021
Max 1hr Temp Fall 1.4 °C 17:05 0.9 °C 1.7 °C, 2012 0.4 °C, 2021
Max 1hr Hum Fall 2% 13:02 3% 12%, 2014 0%, 2013
Max 10m Wind Speed 8.1 mph 02:49 7.0 mph 14.9 mph, 2023 3.0 mph, 2013
Minimum Feels-like 4.1 °C 00:04 -0.5 °C 4.1 °C, 2020 -6.8 °C, 2017
Maximum Feels-like 11.8 °C 14:15 6.2 °C 11.9 °C, 2021 -0.9 °C, 2017
Mean Feels-like 8.3 °C 3.2 °C 8.4 °C, 2023 -3.5 °C, 2017
Air-frost Hrs 0 hrs 0.4 hrs 24 hrs, 2022 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 4.1 °C (-0.5) 3.5 °C (-1.3) 8.5 °C (+3.9), 2021 1.4 °C (-3.2), 2024
Humidity Range 6% 9% 21%, 2014 2%, 2009
Pressure Range 7 hPa 11 hPa 20 hPa, 2017 2 hPa, 2024
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]14 hrs (60%) [18%] 7 [99%], 2012 0 [0%], 2011
Wet Hours 5
[Mean rain rate: 1.5 mm/h]		33 hrs (148%) [12%] 13, 2017 0, 2009
Cloud Cover Overcast or Mostly Cloudy
Events None
Comments o.night rn; 1430 sh
Extra Comments
Issues wind from harpenden
Observer Absent? Yes - observations may be unreliable
Pond Temperature @ Hampstead Heath 6.5 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 11th December 2020.
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 derived based on analysis of webcam observations, but may use data from our closest site, Heathrow, when needed.
Wet hrs are dervied algorithmically from rainfall data, though may be adjusted manually.
Rainfall totals may be manually adjusted after the fact to correct delayed or erroneous data.
Cloud cover and Events are manually reported, often with multi-week delays.
Data is generally reliable and accurate but should always be viewed with some quantity of salt to hand.
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Daily Graph of Conditions

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Webcam Summary of Cloud Conditions

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Wind rose