Daily Report for 31st December 2011

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 10.6 °C (+7.3) 00:08 4.3 °C (+0.7) 12.6 °C (+9.3), 2021 -1.8 °C (-5.1), 2020
Maximum Temperature 12.5 °C (+4.7) 17:14 9.1 °C (+0.9) 14.7 °C (+6.9), 2021 0.8 °C (-7.0), 2020
Mean Temperature 11.7 °C (+6.0) 6.8 °C (+0.8) 13.4 °C, 2021 -0.3 °C, 2020
Minimum Humidity 86% 14:51 71% 89%, 2020 62%, 2015
Maximum Humidity 96% 00:34 90% 98%, 2009 83%, 2016
Mean Humidity 91% 81% 95%, 2010 74%, 2015
Minimum Pressure 1008 hPa 12:01 1007 hPa 1035 hPa, 2018 986 hPa, 2023
Maximum Pressure 1011 hPa 10:10 1016 hPa 1038 hPa, 2018 996 hPa, 2023
Mean Pressure 1010 hPa 1011 hPa 1036 hPa, 2018 990 hPa, 2023
Mean Wind Speed 7.5 mph (+2.4) 6.2 mph (+1.1) 10.7 mph, 2022 1.5 mph, 2010
Maximum Wind Speed 14.3 mph 15.5 mph 24.1 mph, 2023 6.4 mph, 2010
Maximum Gust 21.0 mph 13:43 22.9 mph 40.3 mph, 2022 8.1 mph, 2010
Mean Wind Direction WSW
Rainfall 0.3 mm 56.2 mm (99%) 11.5 mm, 2023
Maximum Hourly Rain 0.3 mm 21:29 5.1 mm, 2017
Maximum 10-min Rain 0.3 mm 21:29 3.3 mm, 2017
Maximum Rain Rate n/a 42, 2015
Minimum Dew Point 9.8 °C 06:56 1.2 °C 10.6 °C, 2021 -2.9 °C, 2020
Maximum Dew Point 10.8 °C 23:55 6.6 °C 12.4 °C, 2021 -0.3 °C, 2020
Mean Dew Point 10.3 °C 3.7 °C 11.3 °C, 2021 -1.4 °C, 2020
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 8.3 °C * 21:00 5.0 °C 12.6 °C, 2021 -1.8 °C, 2020
Day Maximum (09-21) 12.5 °C 15:00 8.7 °C 14.7 °C, 2021 0.8 °C, 2020
Max 10m Temp Rise 0.2 °C 11:37 0.3 °C 0.5 °C, 2019 0.1 °C, 2009
Max 1hr Temp Rise 0.6 °C 12:28 1.0 °C 2.0 °C, 2022 0.3 °C, 2009
Max 1hr Hum Rise 3% 23:18 5% 11%, 2023 1%, 2010
Max 10m Temp Fall 0.1 °C 21:57 0.3 °C 1.4 °C, 2023 0.1 °C, 2010
Max 1hr Temp Fall 0.3 °C 21:57 0.9 °C 3.4 °C, 2023 0.3 °C, 2010
Max 1hr Hum Fall 2% 10:13 4% 9%, 2015 1%, 2016
Max 10m Wind Speed 11.5 mph 03:06 9.2 mph 16.6 mph, 2024 5.0 mph, 2010
Minimum Feels-like 11.7 °C 00:00 0.7 °C 14.5 °C, 2021 -7.1 °C, 2020
Maximum Feels-like 14.1 °C 19:12 8.5 °C 17.1 °C, 2021 0.8 °C, 2020
Mean Feels-like 13.1 °C 5.0 °C 15.4 °C, 2021 -2.1 °C, 2020
Air-frost Hrs 0 hrs 0.2 hrs 13 hrs, 2020 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 1.9 °C (-2.6) 4.8 °C (+0.3) 6.6 °C (+2.1), 2014 1.2 °C (-3.3), 2018
Humidity Range 10% 19% 26%, 2015 3%, 2016
Pressure Range 3 hPa 9 hPa 16 hPa, 2012 3 hPa, 2018
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]68 hrs (104%) [31%] 6 [85%], 2015 0 [0%], 2010
Wet Hours 160 hrs (97%) [8.1%] 7, 2012 0, 2010
Cloud Cover Overcast
Events None
Comments 21, 23 Light/Moderate Showers
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature @ Hampstead Heath 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 31st December 2011.
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