Daily Report for 23rd December 2019

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 5.7 °C (+2.7) 03:22 4.1 °C (+0.8) 10.8 °C (+7.8), 2014 -3.9 °C (-6.9), 2009
Maximum Temperature 10.0 °C (+2.6) 13:33 9.3 °C (+1.2) 12.9 °C (+5.5), 2012 1.9 °C (-5.5), 2010
Mean Temperature 7.8 °C (+2.7) 6.9 °C (+1.0) 11.7 °C, 2014 -0.5 °C, 2009
Minimum Humidity 71% 13:48 78% 98%, 2009 63%, 2015
Maximum Humidity 93% 03:55 94% 98%, 2009 76%, 2014
Mean Humidity 85% 87% 98%, 2009 72%, 2014
Minimum Pressure 998 hPa 00:00 997 hPa 1030 hPa, 2017 978 hPa, 2013
Maximum Pressure 1013 hPa 18:51 1010 hPa 1037 hPa, 2017 991 hPa, 2009
Mean Pressure 1008 hPa 1004 hPa 1033 hPa, 2017 990 hPa, 2009
Mean Wind Speed 6.1 mph (+1.0) 6.1 mph (+1.0) 12.1 mph, 2013 1.5 mph, 2009
Maximum Wind Speed 11.2 mph 12:05 15.2 mph 31.7 mph, 2013 8.1 mph, 2009
Maximum Gust 24.2 mph 15:21 25.0 mph 47.6 mph, 2013 13.8 mph, 2009
Mean Wind Direction SW
Rainfall 0.0 mm 86.0 mm (211%) 15.2 mm, 2013
Maximum Hourly Rain n/a 2.8, 2011
Maximum 10-min Rain n/a 1.4, 2011
Maximum Rain Rate n/a 20, 2011
Minimum Dew Point 4.3 °C 03:06 2.2 °C 7.1 °C, 2012 -4.8 °C, 2010
Maximum Dew Point 6.1 °C 23:33 7.1 °C 12.6 °C, 2012 -1.9 °C, 2010
Mean Dew Point 5.4 °C 4.8 °C 9.8 °C, 2020 -3.0 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 5.7 °C 03:20 4.8 °C 11.8 °C, 2012 -3.9 °C, 2009
Day Maximum (09-21) 10.0 °C 13:37 9.1 °C 12.8 °C, 2014 1.9 °C, 2010
Max 10m Temp Rise 0.4 °C 09:40 0.3 °C 0.4 °C, 2009 0.1 °C, 2011
Max 1hr Temp Rise 1.0 °C 04:54 1.2 °C 1.5 °C, 2009 0.3 °C, 2012
Max 1hr Hum Rise 5% 16:01 5% 9%, 2011 0%, 2009
Max 10m Temp Fall 0.2 °C 14:56 0.4 °C 1.4 °C, 2018 0.1 °C, 2012
Max 1hr Temp Fall 0.9 °C 16:01 1.3 °C 4.2 °C, 2018 0.3 °C, 2013
Max 1hr Hum Fall 6% 06:39 6% 8%, 2014 0%, 2009
Max 10m Wind Speed 11.1 mph 12:13 11.7 mph 23.2 mph, 2013 7.2 mph, 2009
Minimum Feels-like 2.3 °C 01:57 -0.1 °C 10.8 °C, 2014 -6.8 °C, 2010
Maximum Feels-like 10.0 °C 13:31 9.0 °C 15.5 °C, 2012 -1.0 °C, 2010
Mean Feels-like 5.0 °C 4.8 °C 12.4 °C, 2012 -3.5 °C, 2010
Air-frost Hrs 0 hrs 0 hrs 13 hrs, 2009 0 hrs, 2011
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 4.3 °C (-0.1) 5.2 °C (+0.4) 7.7 °C (+3.3), 2009 2.0 °C (-2.4), 2014
Humidity Range 22% 16% 27%, 2015 0%, 2009
Pressure Range 15 hPa 13 hPa 34 hPa, 2013 2 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 4.3 [62%]60 hrs (142%) [37%] 5.3 [76%], 2015 0 [0%], 2010
Wet Hours 096 hrs (209%) [17%] 13, 2013 0, 2010
Cloud Cover am: Sunny
pm: Partly Cloudy
Events None
Comments -
Extra Comments
Issues server CPU pegged til 20 -some data issues
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 5.0 °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

daycamsumFull resolution individual images at up-to 5 minute intervals

Wind rose