Daily Report for 12th December 2019

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 1.4 °C (-1.9) 03:29 2.7 °C (-0.7) 5.8 °C (+2.5), 2015 -4.7 °C (-8.0), 2012
Maximum Temperature 8.7 °C (+0.6) 14:49 9.1 °C (+0.6) 13.2 °C (+5.1), 2015 2.1 °C (-6.0), 2012
Mean Temperature 5.7 °C (-0.7) 6.1 °C (-0.0) 10.0 °C, 2015 -1.1 °C, 2012
Minimum Humidity 88% 08:47 77% 97%, 2013 63%, 2018
Maximum Humidity 94% 13:05 93% 98%, 2009 88%, 2015
Mean Humidity 92% 87% 98%, 2013 79%, 2018
Minimum Pressure 972 hPa 23:56 1006 hPa 1029 hPa, 2009 972 hPa, 2019
Maximum Pressure 1004 hPa 00:00 1020 hPa 1033 hPa, 2009 1004 hPa, 2019
Mean Pressure 989 hPa 1014 hPa 1031 hPa, 2009 989 hPa, 2019
Mean Wind Speed 5.8 mph (+0.7) 6.1 mph (+1.0) 7.8 mph, 2015 1.1 mph, 2012
Maximum Wind Speed 16.8 mph 16:05 15.5 mph 22.5 mph, 2011 6.8 mph, 2016
Maximum Gust 26.5 mph 14:08 24.5 mph 40.9 mph, 2011 9.7 mph, 2012
Mean Wind Direction SSW
Rainfall 8.8 mm 23.5 mm (110%) 10.7 mm, 2014
Maximum Hourly Rain 2.2 mm 16:22 3.0 mm, 2014
Maximum 10-min Rain 0.9 mm 15:49 1.1 mm, 2014
Maximum Rain Rate 7 mm/h 15:43 18 mm/h, 2014
Minimum Dew Point 0.2 °C 03:29 0.9 °C 3.5 °C, 2015 -5.1 °C, 2012
Maximum Dew Point 7.5 °C 14:49 6.9 °C 9.9 °C, 2015 1.4 °C, 2012
Mean Dew Point 4.4 °C 4.0 °C 6.9 °C, 2015 -2.2 °C, 2012
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 1.4 °C 04:14 3.7 °C 8.5 °C, 2014 -4.7 °C, 2012
Day Maximum (09-21) 8.7 °C 14:51 9.0 °C 13.2 °C, 2015 2.1 °C, 2012
Max 10m Temp Rise 0.4 °C 08:09 0.4 °C 0.6 °C, 2013 0.2 °C, 2014
Max 1hr Temp Rise 1.4 °C 08:59 1.3 °C 2.2 °C, 2013 0.4 °C, 2018
Max 1hr Hum Rise 3% 09:59 5% 9%, 2014 0%, 2013
Max 10m Temp Fall 0.2 °C 16:26 0.4 °C 0.5 °C, 2014 0.1 °C, 2015
Max 1hr Temp Fall 0.7 °C 16:45 1.3 °C 1.5 °C, 2010 0.2 °C, 2015
Max 1hr Hum Fall 3% 07:23 6% 9%, 2014 1%, 2013
Max 10m Wind Speed 11.5 mph 16:01 11.5 mph 15.4 mph, 2011 5.5 mph, 2012
Minimum Feels-like -2.9 °C 02:03 -1.6 °C 3.5 °C, 2016 -7.9 °C, 2017
Maximum Feels-like 7.2 °C 17:44 9.0 °C 14.1 °C, 2015 2.1 °C, 2012
Mean Feels-like 2.9 °C 4.2 °C 9.6 °C, 2015 -2.2 °C, 2017
Air-frost Hrs 0 hrs 0 hrs 12 hrs, 2012 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 7.3 °C (+2.5) 6.4 °C (+1.4) 8.6 °C (+3.8), 2013 3.6 °C (-1.2), 2009
Humidity Range 6% 16% 28%, 2018 1%, 2013
Pressure Range 32 hPa 14 hPa 32 hPa, 2019 3 hPa, 2010
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]36 hrs (161%) [42%] 6.3 [89%], 2017 0 [0%], 2014
Wet Hours 7
[Mean rain rate: 1.3 mm/h]
27 hrs (112%) [9.4%] 7, 2014 0, 2009
Cloud Cover Overcast
Events None
Comments rn
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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