Daily Report for 15th December 2011

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 4.0 °C (+0.4) 12:04 3.6 °C (-0.2) 10.3 °C (+6.7), 2021 -5.1 °C (-8.7), 2022
Maximum Temperature 7.9 °C (-0.1) 14:07 8.8 °C (+0.2) 13.6 °C (+5.6), 2015 0.4 °C (-7.6), 2022
Mean Temperature 5.8 °C (+0.2) 6.4 °C (+0.0) 11.9 °C, 2021 -2.1 °C, 2022
Minimum Humidity 65% 21:30 65% 90%, 2013 65%, 2011
Maximum Humidity 84% 23:59 88% 97%, 2010 83%, 2016
Mean Humidity 75% 78% 95%, 2013 75%, 2011
Minimum Pressure 988 hPa 23:55 999 hPa 1030 hPa, 2023 984 hPa, 2012
Maximum Pressure 1001 hPa 15:58 1009 hPa 1040 hPa, 2023 997 hPa, 2012
Mean Pressure 994 hPa 1004 hPa 1037 hPa, 2023 991 hPa, 2012
Mean Wind Speed 7.1 mph (+2.0) 6.5 mph (+1.4) 8.6 mph, 2018 2.2 mph, 2009
Maximum Wind Speed 19.2 mph 17.1 mph 19.2 mph, 2011 6.9 mph, 2009
Maximum Gust 27.7 mph 05:40 25.5 mph 30.0 mph, 2019 10.7 mph, 2009
Mean Wind Direction SW
Rainfall 2.2 mm 30.4 mm (110%) 11.2 mm, 2018
Maximum Hourly Rain 1.4 mm 23:57 4.2 mm, 2019
Maximum 10-min Rain 0.3 mm 23:57 2.4 mm, 2019
Maximum Rain Rate 1.3 mm/h 22:44 26 mm/h, 2019
Minimum Dew Point 0.5 °C 00:20 -0.0 °C 8.4 °C, 2021 -6.6 °C, 2022
Maximum Dew Point 3.4 °C 13:57 5.8 °C 12.2 °C, 2015 -1.7 °C, 2022
Mean Dew Point 1.8 °C 2.7 °C 10.3 °C, 2013 -4.2 °C, 2022
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 4.0 °C 00:04 4.3 °C 10.3 °C, 2021 -5.1 °C, 2022
Day Maximum (09-21) 7.9 °C 14:06 8.3 °C 12.9 °C, 2021 0.4 °C, 2022
Max 10m Temp Rise 0.4 °C 20:50 0.4 °C 0.5 °C, 2009 0.2 °C, 2015
Max 1hr Temp Rise 1.0 °C 05:09 1.2 °C 1.7 °C, 2022 0.4 °C, 2021
Max 1hr Hum Rise 9% 23:06 6% 9%, 2011 2%, 2013
Max 10m Temp Fall 0.2 °C 17:09 0.3 °C 1.2 °C, 2019 0.1 °C, 2015
Max 1hr Temp Fall 0.7 °C 23:05 0.9 °C 2.3 °C, 2019 0.2 °C, 2015
Max 1hr Hum Fall 4% 21:52 5% 7%, 2009 1%, 2015
Max 10m Wind Speed 12.4 mph 06:08 11.5 mph 14.3 mph, 2018 4.9 mph, 2009
Minimum Feels-like 0.0 °C 02:15 0.1 °C 11.2 °C, 2021 -10.5 °C, 2022
Maximum Feels-like 4.7 °C 15:26 8.1 °C 16.0 °C, 2015 0.4 °C, 2022
Mean Feels-like 2.2 °C 4.3 °C 12.9 °C, 2015 -4.3 °C, 2022
Air-frost Hrs 0 hrs 0 hrs 22 hrs, 2022 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 3.9 °C (-0.5) 5.2 °C (+0.4) 5.9 °C (+1.5), 2014 2.3 °C (-2.1), 2009
Humidity Range 19% 23% 29%, 2018 3%, 2015
Pressure Range 13 hPa 10 hPa 21 hPa, 2017 2 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 3 [43%]48 hrs (151%) [45%] 7 [100%], 2022 0 [0%], 2010
Wet Hours 2.5
[Mean rain rate: 0.9 mm/h]
24 hrs (81%) [6.8%] 7, 2018 0, 2009
Cloud Cover am: Sunny
pm: Mostly Cloudy
Events None
Comments 05 Light Shower; 22- Light Rain
Extra Comments
Issues Wind sensor failure: no data from 06z - data reconstructed using nearby sites
Observer Absent? No
Pond Temperature (Heath) 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 15th 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