Daily Report for 4th December 2019

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 0.1 °C (-3.5) 22:15 1.1 °C (-2.6) 6.1 °C (+2.5), 2015 0.1 °C (-3.5), 2019
Maximum Temperature 7.4 °C (-1.4) 13:33 7.1 °C (-1.7) 12.8 °C (+4.0), 2015 5.2 °C (-3.6), 2020
Mean Temperature 3.1 °C (-2.4) 3.7 °C (-2.1) 10.0 °C, 2015 3.1 °C, 2019
Minimum Humidity 77% 13:59 76% 85%, 2010 51%, 2016
Maximum Humidity 97% 09:37 94% 97%, 2009 78%, 2016
Mean Humidity 90% 87% 93%, 2010 69%, 2016
Minimum Pressure 1020 hPa 15:48 1023 hPa 1030 hPa, 2017 973 hPa, 2020
Maximum Pressure 1024 hPa 00:01 1030 hPa 1036 hPa, 2017 985 hPa, 2020
Mean Pressure 1022 hPa 1026 hPa 1033 hPa, 2017 978 hPa, 2020
Mean Wind Speed 0.7 mph (-4.4) 3.2 mph (-1.9) 8.3 mph, 2015 0.7 mph, 2019
Maximum Wind Speed 5.1 mph 12:43 8.9 mph 23.7 mph, 2015 5.1 mph, 2019
Maximum Gust 8.0 mph 13:22 14.2 mph 36.7 mph, 2015 8.0 mph, 2019
Mean Wind Direction S
Rainfall 0.0 mm 0.0 mm (0%) 3.8 mm, 2020
Maximum Hourly Rain n/a 0.9, 2018
Maximum 10-min Rain n/a 0.5, 2020
Maximum Rain Rate n/a 18, 2020
Minimum Dew Point -0.9 °C 22:15 -0.6 °C 2.8 °C, 2015 -3.1 °C, 2016
Maximum Dew Point 4.3 °C 12:51 4.0 °C 10.9 °C, 2015 0.6 °C, 2016
Mean Dew Point 1.6 °C 1.8 °C 6.0 °C, 2015 -1.4 °C, 2016
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 0.6 °C * 08:25 1.4 °C 7.3 °C, 2011 -1.4 °C, 2010
Day Maximum (09-21) 7.4 °C 13:36 7.1 °C 12.3 °C, 2015 3.7 °C, 2014
Max 10m Temp Rise 0.7 °C 22:34 0.5 °C 1.1 °C, 2009 0.1 °C, 2011
Max 1hr Temp Rise 2.1 °C 11:49 1.7 °C 2.2 °C, 2009 0.2 °C, 2014
Max 1hr Hum Rise 6% 16:35 4% 11%, 2009 2%, 2020
Max 10m Temp Fall 0.5 °C 15:58 0.4 °C 0.6 °C, 2013 0.2 °C, 2010
Max 1hr Temp Fall 2.2 °C 16:34 1.4 °C 2.5 °C, 2015 0.5 °C, 2010
Max 1hr Hum Fall 9% 11:45 6% 14%, 2012 3%, 2010
Max 10m Wind Speed 3.6 mph 13:27 6.8 mph 15.1 mph, 2015 3.6 mph, 2019
Minimum Feels-like -2.6 °C 01:07 -3.2 °C 2.1 °C, 2015 -3.8 °C, 2010
Maximum Feels-like 7.4 °C 13:34 6.5 °C 14.5 °C, 2015 4.2 °C, 2020
Mean Feels-like 2.8 °C 1.9 °C 9.1 °C, 2015 0.7 °C, 2020
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 7.3 °C (+2.1) 6.0 °C (+0.8) 7.3 °C (+2.1), 2019 2.3 °C (-2.9), 2020
Humidity Range 20% 17% 28%, 2012 12%, 2010
Pressure Range 4 hPa 6 hPa 17 hPa, 2015 1 hPa, 2012
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 7.2 [100%]22 hrs (292%) [76%] 7.2 [100%], 2019 0 [0%], 2010
Wet Hours 00 hrs (0%) [0%] 6, 2020 0, 2012
Cloud Cover Sunny
Events Maximum possible sunshine
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