Daily Report for 17th August 2020

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 15.1 °C (+1.0) 02:58 16.7 °C (+2.4) 18.1 °C (+4.0), 2012 10.8 °C (-3.3), 2018
Maximum Temperature 23.2 °C (+0.8) 15:47 27.3 °C (+4.5) 27.6 °C (+5.2), 2012 18.2 °C (-4.2), 2021
Mean Temperature 18.2 °C (+0.9) 21.7 °C (+3.4) 22.2 °C, 2012 15.4 °C, 2021
Minimum Humidity 62% 15:56 50% 76%, 2021 33%, 2012
Maximum Humidity 98% 07:27 88% 98%, 2020 76%, 2012
Mean Humidity 85% 71% 90%, 2022 58%, 2012
Minimum Pressure 1008 hPa 16:09 1014 hPa 1019 hPa, 2021 1004 hPa, 2019
Maximum Pressure 1010 hPa 00:18 1017 hPa 1023 hPa, 2023 1006 hPa, 2019
Mean Pressure 1009 hPa 1016 hPa 1021 hPa, 2023 1005 hPa, 2019
Mean Wind Speed 2.2 mph (-1.8) 3.5 mph (-0.5) 7.6 mph, 2014 1.9 mph, 2015
Maximum Wind Speed 14.2 mph 16:24 11.6 mph 17.6 mph, 2014 9.0 mph, 2015
Maximum Gust 23.0 mph 16:27 17.9 mph 26.8 mph, 2013 12.1 mph, 2011
Mean Wind Direction SW
Rainfall 1.7 mm 25.2 mm (85%) 35.8 mm, 2022
Maximum Hourly Rain 1.2 mm 16:55 23.1 mm, 2022
Maximum 10-min Rain 0.8 mm 16:33 9.9 mm, 2022
Maximum Rain Rate 10 mm/h 16:31 90 mm/h, 2022
Minimum Dew Point 14.1 °C 02:55 13.5 °C 15.4 °C, 2022 4.1 °C, 2014
Maximum Dew Point 17.4 °C 17:43 18.1 °C 19.2 °C, 2022 11.3 °C, 2015
Mean Dew Point 15.6 °C 15.8 °C 16.9 °C, 2022 8.0 °C, 2015
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 15.1 °C 02:55 17.0 °C 18.1 °C, 2012 10.8 °C, 2018
Day Maximum (09-21) 23.2 °C 15:48 27.3 °C 27.6 °C, 2012 18.2 °C, 2021
Max 10m Temp Rise 0.7 °C 07:29 0.7 °C 1.0 °C, 2009 0.3 °C, 2010
Max 1hr Temp Rise 2.2 °C 08:06 2.7 °C 3.1 °C, 2018 0.9 °C, 2010
Max 1hr Hum Rise 19% 17:26 10% 22%, 2022 3%, 2015
Max 10m Temp Fall 1.4 °C 16:33 0.7 °C 1.8 °C, 2022 0.3 °C, 2010
Max 1hr Temp Fall 3.3 °C 16:53 2.2 °C 5.0 °C, 2022 0.7 °C, 2021
Max 1hr Hum Fall 11% 14:29 11% 27%, 2014 4%, 2010
Max 10m Wind Speed 10.7 mph 16:30 8.2 mph 13.1 mph, 2014 5.8 mph, 2015
Minimum Feels-like 18.5 °C 02:44 20.3 °C 20.6 °C, 2012 11.8 °C, 2018
Maximum Feels-like 27.8 °C 15:41 32.5 °C 30.9 °C, 2022 20.6 °C, 2015
Mean Feels-like 22.6 °C 26.4 °C 25.0 °C, 2012 17.2 °C, 2015
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 8.1 °C (-0.2) 10.6 °C (+2.1) 12.0 °C (+3.7), 2016 5.2 °C (-3.1), 2010
Humidity Range 36% 38% 49%, 2016 13%, 2021
Pressure Range 2 hPa 3 hPa 10 hPa, 2013 2 hPa, 2011
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 2.5 [19%]111 hrs (107%) [48%] 12 [91%], 2016 0 [0%], 2021
Wet Hours 1.5
[Mean rain rate: 1.1 mm/h]		14 hrs (68%) [3.5%] 5, 2022 0, 2009
Cloud Cover Mostly Cloudy with periods of Partly Cloudy
Events Thunder
Comments 13, 1630, 1830 Showers, probs with thunder
Extra Comments
Issues Rain gauge blocked, tips come from yesterday
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 22.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 17th August 2020.
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

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Wind rose