Daily Report for 11th December 2019

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 2.6 °C (-0.8) 23:50 2.9 °C (-0.6) 6.7 °C (+3.4), 2020 -3.4 °C (-6.8), 2012
Maximum Temperature 7.9 °C (-0.3) 13:05 9.2 °C (+0.6) 10.8 °C (+2.6), 2020 1.7 °C (-6.5), 2012
Mean Temperature 5.4 °C (-0.5) 6.2 °C (+0.0) 9.1 °C, 2015 -0.6 °C, 2012
Minimum Humidity 76% 13:03 76% 96%, 2009 65%, 2014
Maximum Humidity 91% 07:28 93% 98%, 2009 79%, 2016
Mean Humidity 87% 86% 98%, 2009 77%, 2014
Minimum Pressure 1002 hPa 15:35 1009 hPa 1032 hPa, 2009 978 hPa, 2017
Maximum Pressure 1010 hPa 01:50 1022 hPa 1034 hPa, 2009 993 hPa, 2020
Mean Pressure 1006 hPa 1016 hPa 1033 hPa, 2009 985 hPa, 2017
Mean Wind Speed 5.3 mph (+0.2) 6.1 mph (+1.0) 8.7 mph, 2014 0.6 mph, 2013
Maximum Wind Speed 13.8 mph 14:23 15.3 mph 18.1 mph, 2014 4.0 mph, 2013
Maximum Gust 22.0 mph 11:33 24.3 mph 25.3 mph, 2014 5.9 mph, 2013
Mean Wind Direction SW
Rainfall 0.0 mm 14.7 mm (75%) 16.1 mm, 2017
Maximum Hourly Rain n/a 5.3, 2011
Maximum 10-min Rain n/a 2, 2011
Maximum Rain Rate n/a 24, 2015
Minimum Dew Point 1.1 °C 23:50 1.0 °C 5.7 °C, 2020 -4.2 °C, 2012
Maximum Dew Point 5.4 °C 00:01 6.8 °C 9.5 °C, 2020 0.1 °C, 2012
Mean Dew Point 3.4 °C 4.0 °C 7.9 °C, 2020 -1.7 °C, 2012
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 3.9 °C * 07:51 3.9 °C 9.5 °C, 2015 -1.2 °C, 2012
Day Maximum (09-21) 7.9 °C 13:09 9.0 °C 10.8 °C, 2020 1.7 °C, 2012
Max 10m Temp Rise 0.3 °C 10:03 0.4 °C 0.6 °C, 2009 0.1 °C, 2015
Max 1hr Temp Rise 1.4 °C 10:16 1.3 °C 2.1 °C, 2018 0.4 °C, 2015
Max 1hr Hum Rise 7% 14:41 5% 9%, 2014 1%, 2009
Max 10m Temp Fall 0.4 °C 14:28 0.4 °C 0.6 °C, 2014 0.2 °C, 2016
Max 1hr Temp Fall 1.0 °C 15:12 1.3 °C 1.7 °C, 2012 0.7 °C, 2016
Max 1hr Hum Fall 6% 12:12 6% 12%, 2014 0%, 2013
Max 10m Wind Speed 9.7 mph 12:15 11.5 mph 13.0 mph, 2014 3.0 mph, 2013
Minimum Feels-like -1.6 °C 23:20 -1.5 °C 4.1 °C, 2020 -6.8 °C, 2017
Maximum Feels-like 6.4 °C 00:07 9.2 °C 11.8 °C, 2020 -0.9 °C, 2017
Mean Feels-like 2.6 °C 4.3 °C 8.3 °C, 2020 -3.5 °C, 2017
Air-frost Hrs 0 hrs 0 hrs 14 hrs, 2012 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 5.3 °C (+0.5) 6.3 °C (+1.3) 7.2 °C (+2.4), 2018 3.1 °C (-1.8), 2017
Humidity Range 15% 17% 21%, 2014 2%, 2009
Pressure Range 8 hPa 12 hPa 20 hPa, 2017 2 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 3.5 [49%]36 hrs (175%) [46%] 7 [99%], 2012 0 [0%], 2011
Wet Hours 020 hrs (91%) [7.6%] 13, 2017 0, 2009
Cloud Cover am: Sunny
pm: Partly Cloudy
Events None
Comments -
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 4.5 °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