Daily Report for 17th September 2026

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 13.4 °C (+2.0) 04:14 14.3 °C (+2.3) 17.3 °C (+5.9), 2018 5.0 °C (-6.4), 2022
Maximum Temperature 20.6 °C (+1.9) 14:43 22.2 °C (+2.3) 24.8 °C (+6.1), 2018 13.4 °C (-5.3), 2013
Mean Temperature 16.2 °C (+1.9) 18.2 °C (+2.3) 20.3 °C, 2018 11.0 °C, 2022
Minimum Humidity 47% 17:55 54% 80%, 2023 36%, 2018
Maximum Humidity 90% 09:34 87% 95%, 2013 84%, 2009
Mean Humidity 68% 72% 89%, 2023 65%, 2012
Minimum Pressure 1011 hPa 14:45 1016 hPa 1030 hPa, 2024 987 hPa, 2015
Maximum Pressure 1018 hPa 00:02 1022 hPa 1033 hPa, 2024 1005 hPa, 2013
Mean Pressure 1013 hPa 1019 hPa 1032 hPa, 2024 999 hPa, 2015
Mean Wind Speed 5.7 mph (+1.8) 5.0 mph (+1.1) 8.3 mph, 2016 2.2 mph, 2017
Maximum Wind Speed 15.0 mph 15:44 13.4 mph 20.5 mph, 2016 8.1 mph, 2014
Maximum Gust 27.6 mph 12:48 22.6 mph 30.6 mph, 2016 12.5 mph, 2014
Mean Wind Direction WNW
Rainfall 1.0 mm 26.2 mm (92%) 5.5 mm, 2013
Maximum Hourly Rain 0.6 mm 07:13 2.6 mm, 2023
Maximum 10-min Rain 0.4 mm 06:51 2.2 mm, 2023
Maximum Rain Rate 0.5 mm/h 07:13 30 mm/h, 2023
Minimum Dew Point 6.8 °C 18:05 10.4 °C 13.9 °C, 2014 2.0 °C, 2022
Maximum Dew Point 14.6 °C 11:02 15.3 °C 17.7 °C, 2023 5.0 °C, 2022
Mean Dew Point 10.1 °C 12.8 °C 16.1 °C, 2023 3.6 °C, 2022
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 13.4 °C 04:16 14.8 °C 17.3 °C, 2018 5.0 °C, 2022
Day Maximum (09-21) 20.6 °C 14:44 22.1 °C 24.8 °C, 2018 13.4 °C, 2013
Max 10m Temp Rise 0.8 °C 12:29 0.6 °C 0.8 °C, 2026 0.3 °C, 2016
Max 1hr Temp Rise 2.7 °C 11:25 2.2 °C 3.1 °C, 2024 0.8 °C, 2016
Max 1hr Hum Rise 7% 07:29 8% 15%, 2020 4%, 2014
Max 10m Temp Fall 0.9 °C 12:04 0.6 °C 0.9 °C, 2026 0.2 °C, 2014
Max 1hr Temp Fall 1.2 °C 19:27 1.8 °C 2.6 °C, 2010 0.3 °C, 2025
Max 1hr Hum Fall 16% 11:59 10% 26%, 2012 2%, 2016
Max 10m Wind Speed 11.1 mph 13:09 9.9 mph 14.0 mph, 2016 6.0 mph, 2019
Minimum Feels-like 14.4 °C 03:48 16.3 °C 20.3 °C, 2018 4.0 °C, 2022
Maximum Feels-like 22.5 °C 11:50 25.7 °C 27.5 °C, 2018 15.4 °C, 2010
Mean Feels-like 17.5 °C 21.0 °C 23.3 °C, 2018 10.0 °C, 2022
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Minimum PM2.5 1 04:55 1 1, 2026 0, 2021
Maximum PM2.5 9 20:45 14 9, 2026 9, 2026
Mean PM2.5 3 4 3, 2026 3, 2026
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 7.2 °C (-0.1) 7.9 °C (+0.0) 12.0 °C (+4.7), 2022 3.9 °C (-3.4), 2014
Humidity Range 43% 33% 52%, 2018 10%, 2016
Pressure Range 7 hPa 5 hPa 20 hPa, 2015 2 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 5.5 [48%]91 hrs (105%) [45%] 11.4 [100%], 2019 0 [0%], 2016
Wet Hours 2
[Mean rain rate: 0.5 mm/h]		26 hrs (112%) [6.4%] 5, 2013 0, 2009
Cloud Cover unknown
Events None
Comments data is awaiting quality control from site operator
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature @ Hampstead Heath 17.5 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 17th September 2026.
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.
View monthly summary

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