Daily Report for 6th September 2011

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 13.0 °C (+0.6) 23:53 12.9 °C (+0.3) 19.3 °C (+6.9), 2016 5.6 °C (-6.8), 2015
Maximum Temperature 17.9 °C (-2.8) 15:23 20.8 °C (-0.1) 30.6 °C (+9.9), 2023 17.9 °C (-2.8), 2011
Mean Temperature 15.5 °C (-1.1) 16.8 °C (+0.1) 22.6 °C, 2023 12.3 °C, 2015
Minimum Humidity 77% 21:10 58% 89%, 2024 37%, 2012
Maximum Humidity 94% 11:35 90% 97%, 2022 77%, 2009
Mean Humidity 85% 75% 94%, 2024 60%, 2012
Minimum Pressure 1004 hPa 17:16 1008 hPa 1026 hPa, 2015 1000 hPa, 2010
Maximum Pressure 1012 hPa 00:38 1012 hPa 1030 hPa, 2012 1010 hPa, 2013
Mean Pressure 1008 hPa 1010 hPa 1028 hPa, 2015 1008 hPa, 2010
Mean Wind Speed 9.8 mph (+5.9) 6.1 mph (+2.2) 9.8 mph, 2011 0.4 mph, 2021
Maximum Wind Speed 21.0 mph 14.6 mph 21.0 mph, 2011 4.6 mph, 2021
Maximum Gust 33.9 mph 07:26 21.1 mph 33.9 mph, 2011 6.4 mph, 2014
Mean Wind Direction SW
Rainfall 21.7 mm 25.8 mm (258%) 21.7 mm, 2011
Maximum Hourly Rain 18.4 mm 17:01 18.4 mm, 2011
Maximum 10-min Rain 7.4 mm 16:28 7.4 mm, 2011
Maximum Rain Rate 100 mm/h 16:28 100 mm/h, 2011
Minimum Dew Point 9.6 °C 23:53 9.5 °C 16.8 °C, 2016 4.1 °C, 2015
Maximum Dew Point 15.7 °C 13:35 14.6 °C 21.6 °C, 2023 10.1 °C, 2015
Mean Dew Point 12.9 °C 12.2 °C 19.0 °C, 2016 6.6 °C, 2015
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 14.9 °C * 09:10 13.5 °C 19.9 °C, 2016 5.6 °C, 2015
Day Maximum (09-21) 17.9 °C 15:23 20.8 °C 30.6 °C, 2023 16.9 °C, 2013
Max 10m Temp Rise 0.2 °C 13:29 0.5 °C 0.9 °C, 2012 0.2 °C, 2011
Max 1hr Temp Rise 0.8 °C 11:30 1.8 °C 4.7 °C, 2012 0.8 °C, 2011
Max 1hr Hum Rise 6% 09:11 8% 16%, 2025 2%, 2024
Max 10m Temp Fall 0.5 °C 16:33 0.4 °C 1.0 °C, 2022 0.3 °C, 2013
Max 1hr Temp Fall 1.9 °C 17:00 1.5 °C 3.3 °C, 2021 1.0 °C, 2018
Max 1hr Hum Fall 6% 18:40 11% 19%, 2012 5%, 2016
Max 10m Wind Speed 13.1 mph 14:51 9.6 mph 14.0 mph, 2025 2.9 mph, 2021
Minimum Feels-like 14.1 °C 23:52 14.3 °C 24.5 °C, 2016 3.9 °C, 2015
Maximum Feels-like 22.1 °C 15:16 23.9 °C 39.2 °C, 2023 18.9 °C, 2015
Mean Feels-like 18.3 °C 19.2 °C 28.6 °C, 2023 12.4 °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 4.9 °C (-3.4) 7.9 °C (-0.4) 15.2 °C (+6.9), 2023 3.9 °C (-4.4), 2016
Humidity Range 17% 32% 52%, 2012 8%, 2024
Pressure Range 8 hPa 4 hPa 20 hPa, 2016 2 hPa, 2023
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]30 hrs (94%) [40%] 11 [91%], 2012 0 [0%], 2011
Wet Hours 5
[Mean rain rate: 4.3 mm/h]		9 hrs (110%) [6.3%] 5, 2011 0, 2009
Cloud Cover Overcast
Events None
Comments 05-11 broken Light Rain; 15-17 Torrential Shower
Extra Comments Torrential rain caused by v. slow moving active cold front
Issues None known
Observer Absent? No
Pond Temperature @ Hampstead Heath 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 6th September 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

day graph

Webcam Summary of Cloud Conditions

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Wind rose