Daily Report for 18th December 2018

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 7.2 °C (+3.8) 23:57 5.1 °C (+1.3) 12.4 °C (+8.9), 2014 -6.0 °C (-9.4), 2010
Maximum Temperature 10.4 °C (+2.7) 04:49 9.9 °C (+1.5) 13.7 °C (+6.0), 2015 0.3 °C (-7.4), 2010
Mean Temperature 9.5 °C (+3.2) 7.8 °C (+1.4) 13.0 °C, 2014 -2.5 °C, 2010
Minimum Humidity 73% 15:43 76% 91%, 2021 73%, 2018
Maximum Humidity 93% 21:32 93% 98%, 2010 82%, 2016
Mean Humidity 85% 86% 94%, 2022 81%, 2016
Minimum Pressure 1002 hPa 20:53 1008 hPa 1039 hPa, 2021 988 hPa, 2013
Maximum Pressure 1018 hPa 00:01 1018 hPa 1041 hPa, 2021 995 hPa, 2010
Mean Pressure 1009 hPa 1013 hPa 1040 hPa, 2021 992 hPa, 2010
Mean Wind Speed 8.6 mph (+3.5) 5.9 mph (+0.8) 10.3 mph, 2020 0.8 mph, 2016
Maximum Wind Speed 19.8 mph 09:05 14.7 mph 21.5 mph, 2014 4.7 mph, 2016
Maximum Gust 33.4 mph 14:09 23.9 mph 34.4 mph, 2013 6.3 mph, 2016
Mean Wind Direction S
Rainfall 4.2 mm 44.7 mm (135%) 10.8 mm, 2022
Maximum Hourly Rain 1.5 mm 18:00 4.2 mm, 2013
Maximum 10-min Rain 0.4 mm 18:00 1.3 mm, 2013
Maximum Rain Rate 1.9 mm/h 17:44 9 mm/h, 2013
Minimum Dew Point 5.4 °C 15:43 2.8 °C 10.4 °C, 2014 -7.8 °C, 2010
Maximum Dew Point 8.6 °C 00:50 7.8 °C 11.5 °C, 2014 -0.4 °C, 2009
Mean Dew Point 7.1 °C 5.5 °C 10.9 °C, 2014 -3.5 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 8.9 °C * 21:16 6.0 °C 12.1 °C, 2014 -6.0 °C, 2010
Day Maximum (09-21) * 10.1 °C * 13:19 9.7 °C 13.7 °C, 2015 0.3 °C, 2010
Max 10m Temp Rise 0.2 °C 00:20 0.3 °C 0.7 °C, 2019 0.2 °C, 2009
Max 1hr Temp Rise 0.5 °C 21:28 1.1 °C 2.8 °C, 2019 0.3 °C, 2021
Max 1hr Hum Rise 10% 16:57 5% 10%, 2018 2%, 2016
Max 10m Temp Fall 0.3 °C 16:29 0.3 °C 0.5 °C, 2017 0.1 °C, 2014
Max 1hr Temp Fall 1.2 °C 17:14 1.0 °C 2.0 °C, 2017 0.3 °C, 2014
Max 1hr Hum Fall 5% 14:12 6% 7%, 2013 1%, 2016
Max 10m Wind Speed 13.7 mph 14:42 11.0 mph 16.2 mph, 2013 3.2 mph, 2016
Minimum Feels-like 3.8 °C 17:39 1.9 °C 14.1 °C, 2014 -8.9 °C, 2010
Maximum Feels-like 11.0 °C 01:25 10.4 °C 15.5 °C, 2014 0.3 °C, 2010
Mean Feels-like 8.1 °C 6.5 °C 14.7 °C, 2014 -4.4 °C, 2009
Air-frost Hrs 0 hrs 0 hrs 21 hrs, 2010 0 hrs, 2012
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 3.2 °C (-1.0) 4.8 °C (+0.1) 11.5 °C (+7.3), 2022 1.2 °C (-3.0), 2014
Humidity Range 20% 16% 20%, 2018 3%, 2016
Pressure Range 16 hPa 10 hPa 27 hPa, 2013 2 hPa, 2021
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]37 hrs (97%) [29%] 7 [100%], 2017 0 [0%], 2010
Wet Hours 5
[Mean rain rate: 0.8 mm/h]
43 hrs (119%) [10%] 10, 2022 0, 2011
Cloud Cover Overcast
Events None
Comments steady eve Rain
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 18th December 2018.
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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Webcam Summary of Cloud Conditions

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