Daily Report for 22nd December 2019

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 6.3 °C (+2.9) 23:51 4.0 °C (+0.4) 11.6 °C (+8.2), 2014 -2.3 °C (-5.7), 2009
Maximum Temperature 8.8 °C (+1.1) 01:27 9.2 °C (+1.0) 14.9 °C (+7.2), 2015 1.3 °C (-6.4), 2009
Mean Temperature 7.8 °C (+2.0) 6.8 °C (+0.7) 13.5 °C, 2015 0.0 °C, 2009
Minimum Humidity 84% 13:06 78% 96%, 2009 59%, 2013
Maximum Humidity 95% 00:16 94% 98%, 2009 83%, 2016
Mean Humidity 90% 87% 98%, 2009 74%, 2013
Minimum Pressure 974 hPa 00:03 997 hPa 1034 hPa, 2017 974 hPa, 2019
Maximum Pressure 998 hPa 23:59 1010 hPa 1037 hPa, 2017 990 hPa, 2009
Mean Pressure 986 hPa 1004 hPa 1036 hPa, 2017 986 hPa, 2019
Mean Wind Speed 5.6 mph (+0.5) 6.1 mph (+1.0) 11.9 mph, 2015 1.7 mph, 2021
Maximum Wind Speed 11.4 mph 09:00 15.4 mph 23.5 mph, 2015 7.2 mph, 2021
Maximum Gust 19.6 mph 09:03 25.0 mph 43.4 mph, 2015 11.4 mph, 2021
Mean Wind Direction WSW
Rainfall 1.8 mm 86.0 mm (213%) 17.8 mm, 2012
Maximum Hourly Rain 0.4 mm 07:05 4.5 mm, 2015
Maximum 10-min Rain 0.4 mm 05:13 2.7 mm, 2015
Maximum Rain Rate 1.4 mm/h 05:13 126 mm/h, 2015
Minimum Dew Point 4.9 °C 23:51 2.1 °C 9.0 °C, 2015 -2.8 °C, 2021
Maximum Dew Point 8.0 °C 00:21 7.2 °C 12.6 °C, 2012 0.9 °C, 2010
Mean Dew Point 6.3 °C 4.8 °C 11.1 °C, 2015 -0.3 °C, 2009
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 7.2 °C * 21:17 4.7 °C 11.2 °C, 2014 -1.4 °C, 2021
Day Maximum (09-21) * 8.7 °C * 14:28 9.1 °C 14.9 °C, 2015 1.3 °C, 2009
Max 10m Temp Rise 0.2 °C 12:56 0.3 °C 0.5 °C, 2021 0.1 °C, 2010
Max 1hr Temp Rise 0.6 °C 13:22 1.2 °C 1.9 °C, 2021 0.2 °C, 2010
Max 1hr Hum Rise 3% 15:33 5% 13%, 2024 1%, 2009
Max 10m Temp Fall 0.3 °C 02:52 0.4 °C 0.7 °C, 2013 0.1 °C, 2012
Max 1hr Temp Fall 0.8 °C 06:10 1.3 °C 1.9 °C, 2016 0.3 °C, 2012
Max 1hr Hum Fall 4% 11:58 6% 12%, 2013 1%, 2012
Max 10m Wind Speed 10.4 mph 11:28 11.7 mph 18.1 mph, 2015 5.4 mph, 2021
Minimum Feels-like 2.9 °C 23:19 -0.2 °C 11.9 °C, 2015 -5.3 °C, 2010
Maximum Feels-like 9.0 °C 00:01 9.0 °C 16.8 °C, 2015 1.1 °C, 2010
Mean Feels-like 5.1 °C 4.8 °C 15.3 °C, 2015 -1.3 °C, 2010
Air-frost Hrs 0 hrs 0 hrs 10 hrs, 2021 0 hrs, 2011
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 2.5 °C (-1.8) 5.2 °C (+0.6) 6.3 °C (+2.0), 2012 1.5 °C (-2.8), 2010
Humidity Range 11% 16% 25%, 2013 2%, 2009
Pressure Range 24 hPa 13 hPa 24 hPa, 2019 3 hPa, 2011
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 3 [43%]56 hrs (121%) [36%] 6.5 [93%], 2011 0 [0%], 2010
Wet Hours 6
[Mean rain rate: 0.3 mm/h]		96 hrs (218%) [18%] 16, 2012 0, 2009
Cloud Cover Partly Cloudy or Hazy
Events None
Comments o.night rn
Extra Comments
Issues server CPU pegged all day -some data issues
Observer Absent? Yes - observations may be unreliable
Pond Temperature @ Hampstead Heath 5.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 22nd December 2019.
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 derived based on analysis of webcam observations, but may use data from our closest site, Heathrow, when needed.
Wet hrs are dervied algorithmically from rainfall data, though may be adjusted manually.
Rainfall totals may be manually adjusted after the fact to correct delayed or erroneous data.
Cloud cover and Events are manually reported, often with multi-week delays.
Data is generally reliable and accurate but should always be viewed with some quantity of salt to hand.
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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