Daily Report for 9th December 2020

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 4.2 °C (+0.5) 00:10 2.1 °C (-1.8) 11.2 °C (+7.4), 2016 -2.2 °C (-6.0), 2022
Maximum Temperature 6.3 °C (-2.1) 13:47 5.7 °C (-3.0) 13.8 °C (+5.4), 2016 2.4 °C (-6.0), 2022
Mean Temperature 5.3 °C (-0.8) 4.0 °C (-2.4) 12.5 °C, 2016 -0.2 °C, 2022
Minimum Humidity 83% 21:00 84% 95%, 2009 58%, 2011
Maximum Humidity 95% 02:02 94% 98%, 2009 77%, 2011
Mean Humidity 89% 89% 97%, 2009 68%, 2011
Minimum Pressure 1002 hPa 23:57 996 hPa 1029 hPa, 2015 990 hPa, 2021
Maximum Pressure 1009 hPa 10:29 1008 hPa 1034 hPa, 2015 1004 hPa, 2021
Mean Pressure 1006 hPa 1002 hPa 1032 hPa, 2015 997 hPa, 2023
Mean Wind Speed 3.2 mph (-1.9) 2.7 mph (-2.4) 9.3 mph, 2023 2.2 mph, 2022
Maximum Wind Speed 10.1 mph 03:19 8.9 mph 23.5 mph, 2023 7.0 mph, 2022
Maximum Gust 17.1 mph 07:01 14.1 mph 34.6 mph, 2018 10.4 mph, 2022
Mean Wind Direction W
Rainfall 1.7 mm 25.3 mm (153%) 8.4 mm, 2023
Maximum Hourly Rain 1.1 mm 01:01 3.8 mm, 2021
Maximum 10-min Rain 0.7 mm 00:11 1.2 mm, 2021
Maximum Rain Rate 4.4 mm/h 00:10 14 mm/h, 2021
Minimum Dew Point 2.5 °C 20:20 0.7 °C 8.9 °C, 2009 -6.5 °C, 2010
Maximum Dew Point 4.3 °C 13:06 3.9 °C 11.7 °C, 2023 -0.4 °C, 2017
Mean Dew Point 3.7 °C 2.3 °C 10.2 °C, 2009 -2.7 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 3.7 °C * 21:14 2.5 °C 12.7 °C, 2016 -2.2 °C, 2022
Day Maximum (09-21) 6.3 °C 13:47 5.7 °C 13.5 °C, 2016 2.4 °C, 2022
Max 10m Temp Rise 0.2 °C 20:34 0.3 °C 0.4 °C, 2013 0.1 °C, 2016
Max 1hr Temp Rise 0.5 °C 10:35 1.0 °C 2.0 °C, 2015 0.3 °C, 2016
Max 1hr Hum Rise 2% 23:57 3% 8%, 2014 1%, 2009
Max 10m Temp Fall 0.2 °C 19:52 0.3 °C 0.7 °C, 2022 0.2 °C, 2010
Max 1hr Temp Fall 0.4 °C 15:44 0.9 °C 2.5 °C, 2022 0.4 °C, 2016
Max 1hr Hum Fall 3% 11:31 3% 12%, 2023 1%, 2016
Max 10m Wind Speed 6.2 mph 04:14 6.8 mph 17.3 mph, 2023 5.6 mph, 2022
Minimum Feels-like 0.0 °C 07:01 -1.2 °C 11.5 °C, 2016 -7.4 °C, 2010
Maximum Feels-like 6.3 °C 13:08 5.4 °C 14.7 °C, 2016 2.4 °C, 2022
Mean Feels-like 3.3 °C 2.5 °C 13.8 °C, 2016 -2.6 °C, 2017
Air-frost Hrs 0 hrs 0.5 hrs 16 hrs, 2022 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 2.1 °C (-2.6) 3.6 °C (-1.3) 11.2 °C (+6.5), 2014 1.4 °C (-3.3), 2024
Humidity Range 12% 10% 27%, 2019 3%, 2009
Pressure Range 7 hPa 11 hPa 35 hPa, 2019 2 hPa, 2022
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]14 hrs (74%) [22%] 7 [99%], 2019 0 [0%], 2020
Wet Hours 2
[Mean rain rate: 0.8 mm/h]		27 hrs (150%) [13%] 10, 2023 0, 2010
Cloud Cover Overcast or Mostly Cloudy
Events None
Comments o.night rn
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 9th 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

day graph

Webcam Summary of Cloud Conditions

daycamsumFull resolution individual images at up-to 5 minute intervals

Wind rose