Daily Report for 30th July 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 14.7 °C (+0.0) 03:32 14.7 °C (+0.4) 17.7 °C (+3.0), 2018 9.1 °C (-5.6), 2011
Maximum Temperature 17.8 °C (-5.5) 12:43 23.4 °C (+0.4) 31.0 °C (+7.7), 2024 17.8 °C (-5.5), 2021
Mean Temperature 16.1 °C (-2.7) 18.9 °C (+0.4) 23.4 °C, 2024 15.2 °C, 2015
Minimum Humidity 74% 00:15 61% 74%, 2021 31%, 2020
Maximum Humidity 91% 06:27 91% 95%, 2009 73%, 2014
Mean Humidity 83% 78% 85%, 2013 54%, 2020
Minimum Pressure 999 hPa 13:25 1014 hPa 1019 hPa, 2025 999 hPa, 2021
Maximum Pressure 1010 hPa 00:07 1018 hPa 1025 hPa, 2011 1008 hPa, 2019
Mean Pressure 1004 hPa 1016 hPa 1022 hPa, 2011 1004 hPa, 2021
Mean Wind Speed 6.0 mph (+1.7) 3.0 mph (-1.3) 7.6 mph, 2019 1.0 mph, 2024
Maximum Wind Speed 18.9 mph 14:28 11.1 mph 19.9 mph, 2019 7.2 mph, 2024
Maximum Gust 29.7 mph 14:11 16.4 mph 36.9 mph, 2019 10.4 mph, 2024
Mean Wind Direction SW
Rainfall 7.2 mm 123.3 mm (277%) 17.8 mm, 2017
Maximum Hourly Rain 2.9 mm 13:45 16.0 mm, 2017
Maximum 10-min Rain 1.7 mm 13:45 5.1 mm, 2017
Maximum Rain Rate 30 mm/h 13:43 50 mm/h, 2017
Minimum Dew Point 11.7 °C 00:15 12.4 °C 13.8 °C, 2024 2.5 °C, 2012
Maximum Dew Point 15.1 °C 13:52 16.9 °C 19.1 °C, 2024 8.9 °C, 2015
Mean Dew Point 13.2 °C 14.7 °C 16.4 °C, 2024 6.2 °C, 2012
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 14.7 °C 03:40 14.9 °C 18.2 °C, 2019 9.1 °C, 2011
Day Maximum (09-21) 17.8 °C 12:44 23.4 °C 31.0 °C, 2024 17.8 °C, 2021
Max 10m Temp Rise 0.7 °C 12:32 0.6 °C 1.0 °C, 2011 0.4 °C, 2016
Max 1hr Temp Rise 1.8 °C 12:43 2.2 °C 4.5 °C, 2011 1.4 °C, 2013
Max 1hr Hum Rise 10% 13:52 11% 19%, 2020 5%, 2013
Max 10m Temp Fall 0.8 °C 13:07 0.7 °C 0.8 °C, 2021 0.3 °C, 2010
Max 1hr Temp Fall 1.3 °C 03:15 2.2 °C 3.0 °C, 2020 1.2 °C, 2010
Max 1hr Hum Fall 10% 07:47 10% 17%, 2018 8%, 2013
Max 10m Wind Speed 15.9 mph 14:45 8.0 mph 15.9 mph, 2021 4.1 mph, 2024
Minimum Feels-like 17.1 °C 03:28 17.4 °C 20.7 °C, 2018 8.2 °C, 2011
Maximum Feels-like 21.5 °C 12:37 28.4 °C 37.5 °C, 2024 18.8 °C, 2015
Mean Feels-like 19.1 °C 22.7 °C 28.3 °C, 2024 15.4 °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 3.1 °C (-5.5) 8.7 °C (-0.1) 16.6 °C (+8.0), 2020 3.1 °C (-5.5), 2021
Humidity Range 17% 30% 56%, 2020 17%, 2021
Pressure Range 10 hPa 5 hPa 12 hPa, 2009 2 hPa, 2012
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 2 [14%]163 hrs (86%) [37%] 14.2 [100%], 2020 0.4 [3%], 2016
Wet Hours 4
[Mean rain rate: 1.8 mm/h]		44 hrs (135%) [6.2%] 8, 2019 0, 2011
Cloud Cover Mostly Cloudy with periods of Partly Cloudy
Events None
Comments shs
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature @ Hampstead Heath 20.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 30th July 2021.
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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