Daily Report for 22nd September 2023

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 10.3 °C (-0.6) 05:35 14.7 °C (+2.9) 15.7 °C (+4.8), 2024 6.0 °C (-4.9), 2012
Maximum Temperature 17.4 °C (-0.6) 15:01 24.3 °C (+4.8) 24.4 °C (+6.4), 2020 13.8 °C (-4.2), 2018
Mean Temperature 13.2 °C (-0.6) 19.3 °C (+3.8) 17.9 °C, 2024 11.1 °C, 2012
Minimum Humidity 65% 13:54 61% 82%, 2024 45%, 2012
Maximum Humidity 96% 06:31 94% 97%, 2017 82%, 2025
Mean Humidity 84% 80% 91%, 2013 66%, 2025
Minimum Pressure 997 hPa 00:05 1012 hPa 1026 hPa, 2013 997 hPa, 2023
Maximum Pressure 1010 hPa 23:55 1017 hPa 1032 hPa, 2021 1007 hPa, 2015
Mean Pressure 1002 hPa 1014 hPa 1028 hPa, 2021 1002 hPa, 2015
Mean Wind Speed 3.5 mph (-0.4) 3.9 mph (-0.0) 6.0 mph, 2009 1.7 mph, 2014
Maximum Wind Speed 12.8 mph 14:42 12.2 mph 14.7 mph, 2016 7.1 mph, 2014
Maximum Gust 18.4 mph 15:31 18.6 mph 26.5 mph, 2020 8.1 mph, 2014
Mean Wind Direction NW
Rainfall 0.5 mm 46.1 mm (126%) 18.6 mm, 2024
Maximum Hourly Rain 0.5 mm 7.9 mm, 2024
Maximum 10-min Rain 0.2 mm 2.0 mm, 2024
Maximum Rain Rate n/a 42, 2015
Minimum Dew Point 9.2 °C 23:57 13.0 °C 15.1 °C, 2024 1.7 °C, 2012
Maximum Dew Point 11.9 °C 10:24 17.8 °C 18.0 °C, 2024 7.7 °C, 2025
Mean Dew Point 10.5 °C 15.5 °C 16.4 °C, 2024 4.7 °C, 2012
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 10.3 °C 05:33 15.1 °C 16.2 °C, 2013 6.0 °C, 2012
Day Maximum (09-21) 17.4 °C 14:06 24.3 °C 24.4 °C, 2020 13.8 °C, 2018
Max 10m Temp Rise 0.6 °C 13:03 0.6 °C 0.8 °C, 2012 0.2 °C, 2018
Max 1hr Temp Rise 2.2 °C 09:53 2.5 °C 3.6 °C, 2010 0.7 °C, 2018
Max 1hr Hum Rise 12% 16:36 10% 14%, 2016 4%, 2024
Max 10m Temp Fall 0.7 °C 16:08 0.5 °C 1.3 °C, 2019 0.2 °C, 2018
Max 1hr Temp Fall 2.1 °C 16:43 1.9 °C 4.2 °C, 2019 0.7 °C, 2018
Max 1hr Hum Fall 12% 11:30 11% 20%, 2020 1%, 2018
Max 10m Wind Speed 8.7 mph 14:50 8.8 mph 11.4 mph, 2016 4.5 mph, 2014
Minimum Feels-like 11.4 °C 05:25 17.7 °C 19.7 °C, 2024 2.9 °C, 2012
Maximum Feels-like 19.3 °C 13:06 29.9 °C 28.3 °C, 2020 13.6 °C, 2018
Mean Feels-like 14.7 °C 23.7 °C 22.8 °C, 2024 10.5 °C, 2012
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 7.1 °C (+0.1) 9.6 °C (+1.9) 12.3 °C (+5.3), 2020 3.6 °C (-3.4), 2018
Humidity Range 31% 33% 49%, 2010 14%, 2015
Pressure Range 12 hPa 5 hPa 12 hPa, 2023 3 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 6 [54%]127 hrs (115%) [50%] 10.7 [97%], 2025 0 [0%], 2018
Wet Hours 0.5
[Mean rain rate: 1.0 mm/h]		26 hrs (85%) [4.8%] 10, 2018 0, 2009
Cloud Cover unknown
Events None
Comments 16 sh rather than tip time
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature @ Hampstead Heath 21.2 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 22nd September 2023.
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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