Daily Report for 25th September 2018

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 3.7 °C (-7.0) 07:01 11.7 °C (-0.0) 15.6 °C (+4.9), 2023 3.7 °C (-7.0), 2018
Maximum Temperature 18.1 °C (+0.5) 15:46 20.2 °C (+0.9) 21.4 °C (+3.8), 2023 13.4 °C (-4.2), 2010
Mean Temperature 11.7 °C (-3.2) 15.7 °C (+0.4) 18.3 °C, 2023 9.5 °C, 2010
Minimum Humidity 43% 15:44 54% 86%, 2021 36%, 2025
Maximum Humidity 92% 07:19 90% 97%, 2013 81%, 2025
Mean Humidity 69% 74% 90%, 2021 62%, 2025
Minimum Pressure 1034 hPa 23:50 1017 hPa 1034 hPa, 2018 988 hPa, 2012
Maximum Pressure 1039 hPa 10:50 1023 hPa 1039 hPa, 2018 989 hPa, 2012
Mean Pressure 1037 hPa 1020 hPa 1037 hPa, 2018 988 hPa, 2012
Mean Wind Speed 2.8 mph (-1.1) 4.8 mph (+0.9) 8.5 mph, 2016 0.8 mph, 2021
Maximum Wind Speed 11.4 mph 14:46 13.8 mph 23.0 mph, 2020 5.9 mph, 2021
Maximum Gust 18.2 mph 14:33 21.4 mph 34.6 mph, 2020 8.1 mph, 2013
Mean Wind Direction SSW
Rainfall 0.0 mm 28.6 mm (69%) 5.2 mm, 2024
Maximum Hourly Rain n/a 3.1, 2024
Maximum 10-min Rain n/a 2.1, 2024
Maximum Rain Rate n/a 30, 2024
Minimum Dew Point 2.9 °C 06:32 8.6 °C 13.1 °C, 2013 2.3 °C, 2010
Maximum Dew Point 7.5 °C 10:07 13.1 °C 16.2 °C, 2013 6.0 °C, 2010
Mean Dew Point 5.6 °C 10.8 °C 14.8 °C, 2021 3.8 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 4.4 °C * 07:02 11.9 °C 16.3 °C, 2021 4.4 °C, 2018
Day Maximum (09-21) 18.1 °C 15:23 20.0 °C 21.4 °C, 2023 13.4 °C, 2010
Max 10m Temp Rise 0.8 °C 08:03 0.6 °C 0.9 °C, 2014 0.2 °C, 2017
Max 1hr Temp Rise 3.3 °C 08:17 2.3 °C 3.3 °C, 2018 0.4 °C, 2021
Max 1hr Hum Rise 8% 18:53 9% 13%, 2019 4%, 2021
Max 10m Temp Fall 0.7 °C 18:35 0.5 °C 0.7 °C, 2018 0.2 °C, 2014
Max 1hr Temp Fall 2.4 °C 18:57 1.7 °C 2.7 °C, 2015 0.9 °C, 2014
Max 1hr Hum Fall 17% 10:45 12% 17%, 2015 2%, 2021
Max 10m Wind Speed 8.7 mph 14:16 9.9 mph 16.6 mph, 2016 3.9 mph, 2021
Minimum Feels-like 4.2 °C 05:25 12.6 °C 18.6 °C, 2023 0.9 °C, 2009
Maximum Feels-like 18.1 °C 14:56 22.3 °C 24.9 °C, 2013 13.4 °C, 2010
Mean Feels-like 11.7 °C 17.6 °C 21.7 °C, 2023 8.6 °C, 2010
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 14.4 °C (+7.5) 8.5 °C (+0.9) 14.4 °C (+7.5), 2018 3.4 °C (-3.5), 2017
Humidity Range 49% 37% 49%, 2018 8%, 2021
Pressure Range 5 hPa 6 hPa 16 hPa, 2024 1 hPa, 2011
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 10.8 [99%]143 hrs (115%) [50%] 10.9 [100%], 2025 0 [0%], 2017
Wet Hours 029 hrs (85%) [4.8%] 5, 2024 0, 2009
Cloud Cover Sunny
Events Maximum possible sunshine
Comments -
Extra Comments
Issues Data from N16. Tmin corrected
Observer Absent? Yes - observations may be unreliable
Pond Temperature @ Hampstead Heath 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 25th September 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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Daily Graph of Conditions

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Webcam Summary of Cloud Conditions

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