Daily Report for 15th August 2011

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 12.1 °C (-2.2) 06:27 14.2 °C (-0.2) 17.9 °C (+3.6), 2022 11.5 °C (-2.8), 2016
Maximum Temperature 21.6 °C (-1.0) 14:18 23.0 °C (+0.0) 29.8 °C (+7.2), 2025 19.9 °C (-2.7), 2015
Mean Temperature 17.4 °C (-1.6) 18.4 °C (-0.1) 23.4 °C, 2025 15.8 °C, 2014
Minimum Humidity 41% 15:06 46% 90%, 2020 39%, 2022
Maximum Humidity 76% 23:59 83% 97%, 2010 76%, 2011
Mean Humidity 58% 65% 93%, 2020 58%, 2017
Minimum Pressure 1011 hPa 00:24 1008 hPa 1024 hPa, 2025 1002 hPa, 2012
Maximum Pressure 1018 hPa 22:01 1014 hPa 1028 hPa, 2025 1007 hPa, 2022
Mean Pressure 1014 hPa 1011 hPa 1026 hPa, 2025 1004 hPa, 2022
Mean Wind Speed 4.7 mph (+0.7) 4.8 mph (+0.8) 6.9 mph, 2019 2.0 mph, 2020
Maximum Wind Speed 12.1 mph 12.7 mph 18.4 mph, 2024 8.3 mph, 2020
Maximum Gust 14.5 mph 12:19 18.0 mph 27.6 mph, 2019 11.8 mph, 2014
Mean Wind Direction W
Rainfall trace 23.8 mm (91%) 9.1, 2022
Maximum Hourly Rain n/a 9.1, 2022
Maximum 10-min Rain n/a 7, 2022
Maximum Rain Rate n/a 114, 2022
Minimum Dew Point 6.8 °C 05:07 8.5 °C 15.9 °C, 2020 5.7 °C, 2015
Maximum Dew Point 11.5 °C 22:59 14.3 °C 19.0 °C, 2020 11.5 °C, 2011
Mean Dew Point 8.7 °C 11.4 °C 17.3 °C, 2020 8.7 °C, 2011
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 12.1 °C 06:25 14.3 °C 18.3 °C, 2022 11.5 °C, 2016
Day Maximum (09-21) 21.6 °C 14:17 23.0 °C 29.8 °C, 2025 19.9 °C, 2015
Max 10m Temp Rise 0.8 °C 07:22 0.6 °C 0.8 °C, 2011 0.2 °C, 2020
Max 1hr Temp Rise 3.3 °C 08:08 2.3 °C 3.5 °C, 2016 0.8 °C, 2020
Max 1hr Hum Rise 12% 20:11 9% 29%, 2022 3%, 2020
Max 10m Temp Fall 0.4 °C 19:45 0.6 °C 1.4 °C, 2022 0.2 °C, 2020
Max 1hr Temp Fall 1.8 °C 20:14 2.0 °C 4.8 °C, 2022 0.4 °C, 2020
Max 1hr Hum Fall 13% 09:54 12% 16%, 2015 3%, 2020
Max 10m Wind Speed 7.4 mph 14:11 8.5 mph 14.5 mph, 2024 5.1 mph, 2020
Minimum Feels-like 12.2 °C 06:16 15.7 °C 21.4 °C, 2020 11.6 °C, 2015
Maximum Feels-like 22.2 °C 13:52 25.4 °C 34.8 °C, 2025 21.2 °C, 2015
Mean Feels-like 18.1 °C 20.5 °C 27.8 °C, 2025 17.4 °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 9.5 °C (+1.2) 8.8 °C (+0.2) 12.9 °C (+4.6), 2025 3.6 °C (-4.7), 2020
Humidity Range 35% 37% 53%, 2022 5%, 2020
Pressure Range 7 hPa 6 hPa 11 hPa, 2014 2 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 7 [52%]77 hrs (83%) [38%] 13 [97%], 2016 0 [0%], 2020
Wet Hours 215 hrs (80%) [4.1%] 3, 2020 0, 2009
Cloud Cover Sunny transitioned to Overcast
Events None
Comments 19-20 Light Rain, -00 broken Slight
Extra Comments
Issues None known
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 15th August 2011.
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

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Wind rose