Daily Report for 27th December 2019

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 4.3 °C (+1.5) 18:46 4.0 °C (+0.8) 12.4 °C (+9.6), 2015 0.2 °C (-2.6), 2016
Maximum Temperature 8.2 °C (+1.0) 14:47 9.3 °C (+1.3) 14.5 °C (+7.3), 2015 4.1 °C (-3.1), 2010
Mean Temperature 6.8 °C (+1.2) 6.9 °C (+1.1) 14.0 °C, 2015 2.3 °C, 2016
Minimum Humidity 86% 13:15 78% 86%, 2018 66%, 2010
Maximum Humidity 95% 20:30 94% 98%, 2013 80%, 2010
Mean Humidity 90% 87% 94%, 2018 71%, 2011
Minimum Pressure 1020 hPa 00:00 999 hPa 1041 hPa, 2016 973 hPa, 2020
Maximum Pressure 1036 hPa 23:59 1013 hPa 1046 hPa, 2016 991 hPa, 2013
Mean Pressure 1030 hPa 1006 hPa 1044 hPa, 2016 978 hPa, 2020
Mean Wind Speed 2.2 mph (-2.9) 5.8 mph (+0.7) 10.5 mph, 2013 0.3 mph, 2018
Maximum Wind Speed 11.8 mph 00:17 15.1 mph 27.8 mph, 2020 4.1 mph, 2018
Maximum Gust 20.0 mph 00:38 24.9 mph 41.1 mph, 2020 5.8 mph, 2018
Mean Wind Direction NNW
Rainfall 0.0 mm 92.4 mm (193%) 11.4 mm, 2020
Maximum Hourly Rain n/a 2.7, 2013
Maximum 10-min Rain n/a 1.3, 2013
Maximum Rain Rate n/a 18, 2013
Minimum Dew Point 3.0 °C 18:42 2.2 °C 9.6 °C, 2015 -3.1 °C, 2016
Maximum Dew Point 6.2 °C 23:20 7.1 °C 12.6 °C, 2015 0.7 °C, 2010
Mean Dew Point 5.3 °C 4.8 °C 11.4 °C, 2015 -1.5 °C, 2016
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 6.6 °C * 04:05 4.8 °C 13.4 °C, 2015 -0.4 °C, 2010
Day Maximum (09-21) 8.2 °C 14:23 9.1 °C 14.5 °C, 2015 2.9 °C, 2017
Max 10m Temp Rise 0.3 °C 20:13 0.3 °C 0.4 °C, 2013 0.1 °C, 2011
Max 1hr Temp Rise 1.2 °C 20:22 1.2 °C 1.5 °C, 2016 0.3 °C, 2011
Max 1hr Hum Rise 4% 19:42 5% 10%, 2013 3%, 2016
Max 10m Temp Fall 0.4 °C 17:11 0.4 °C 1.2 °C, 2014 0.2 °C, 2010
Max 1hr Temp Fall 1.6 °C 17:11 1.3 °C 4.9 °C, 2014 0.7 °C, 2010
Max 1hr Hum Fall 2% 09:49 6% 13%, 2013 1%, 2015
Max 10m Wind Speed 7.7 mph 00:33 11.5 mph 22.5 mph, 2020 3.3 mph, 2018
Minimum Feels-like 0.9 °C 01:07 -0.1 °C 13.9 °C, 2015 -6.3 °C, 2017
Maximum Feels-like 8.2 °C 14:32 9.0 °C 17.0 °C, 2015 4.0 °C, 2010
Mean Feels-like 5.8 °C 4.9 °C 16.0 °C, 2015 -1.4 °C, 2017
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 3.9 °C (-0.5) 5.3 °C (+0.5) 9.2 °C (+4.8), 2020 1.6 °C (-2.8), 2010
Humidity Range 9% 15% 32%, 2013 9%, 2019
Pressure Range 17 hPa 13 hPa 23 hPa, 2012 2 hPa, 2018
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0.4 [6%]70 hrs (140%) [36%] 5 [71%], 2016 0 [0%], 2010
Wet Hours 0105 hrs (194%) [16%] 8, 2017 0, 2009
Cloud Cover Overcast with periods of Partly Cloudy
Events None
Comments -
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 5.5 °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