Daily Report for 17th July 2011

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 12.8 °C (-1.6) 05:23 12.9 °C (-1.0) 18.7 °C (+4.3), 2016 12.7 °C (-1.7), 2023
Maximum Temperature 18.9 °C (-4.3) 13:21 21.2 °C (-1.6) 31.2 °C (+8.0), 2013 18.4 °C (-4.8), 2009
Mean Temperature 15.6 °C (-3.0) 17.2 °C (-1.3) 24.7 °C, 2013 15.6 °C, 2009
Minimum Humidity 64% 18:35 47% 71%, 2009 29%, 2013
Maximum Humidity 85% 06:35 81% 96%, 2009 71%, 2013
Mean Humidity 77% 64% 88%, 2009 45%, 2013
Minimum Pressure 993 hPa 13:20 1011 hPa 1028 hPa, 2021 993 hPa, 2011
Maximum Pressure 996 hPa 12:00 1015 hPa 1030 hPa, 2021 996 hPa, 2011
Mean Pressure 994 hPa 1013 hPa 1029 hPa, 2021 994 hPa, 2011
Mean Wind Speed 7.1 mph (+2.8) 4.9 mph (+0.6) 8.5 mph, 2009 1.3 mph, 2024
Maximum Wind Speed 15.9 mph 12.4 mph 16.6 mph, 2016 6.3 mph, 2024
Maximum Gust 22.8 mph 17:40 17.6 mph 26.0 mph, 2009 10.4 mph, 2024
Mean Wind Direction SW
Rainfall 3.3 mm 31.1 mm (123%) 3.3 mm, 2011
Maximum Hourly Rain 1.6 mm 14:20 1.6 mm, 2011
Maximum 10-min Rain 1.1 mm 13:29 1.1 mm, 2011
Maximum Rain Rate 50 mm/h 13:24 50 mm/h, 2011
Minimum Dew Point 8.9 °C 00:04 7.2 °C 13.6 °C, 2016 4.2 °C, 2010
Maximum Dew Point 14.6 °C 16:11 12.3 °C 18.3 °C, 2021 12.7 °C, 2010
Mean Dew Point 11.4 °C 9.7 °C 15.8 °C, 2016 9.2 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 12.8 °C 05:25 13.1 °C 18.7 °C, 2016 12.7 °C, 2023
Day Maximum (09-21) 18.9 °C 13:20 21.2 °C 31.2 °C, 2013 18.4 °C, 2009
Max 10m Temp Rise 0.6 °C 14:49 0.6 °C 1.6 °C, 2009 0.4 °C, 2017
Max 1hr Temp Rise 1.7 °C 13:21 2.4 °C 4.8 °C, 2022 1.7 °C, 2011
Max 1hr Hum Rise 9% 21:10 10% 19%, 2022 5%, 2010
Max 10m Temp Fall 0.5 °C 13:37 0.5 °C 1.1 °C, 2009 0.3 °C, 2012
Max 1hr Temp Fall 1.6 °C 14:22 1.7 °C 3.0 °C, 2022 1.1 °C, 2012
Max 1hr Hum Fall 14% 17:47 10% 21%, 2022 7%, 2014
Max 10m Wind Speed 11.4 mph 17:08 8.7 mph 14.2 mph, 2015 4.6 mph, 2024
Minimum Feels-like 13.9 °C 00:11 13.8 °C 23.2 °C, 2016 13.9 °C, 2011
Maximum Feels-like 21.9 °C 13:20 22.7 °C 33.8 °C, 2021 21.9 °C, 2011
Mean Feels-like 17.6 °C 18.5 °C 26.8 °C, 2016 17.6 °C, 2011
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 6.1 °C (-2.7) 8.3 °C (-0.7) 15.8 °C (+7.0), 2022 4.5 °C (-4.3), 2009
Humidity Range 21% 34% 52%, 2022 21%, 2011
Pressure Range 3 hPa 5 hPa 11 hPa, 2010 2 hPa, 2016
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 2 [14%]93 hrs (86%) [37%] 14.7 [100%], 2021 1.5 [10%], 2009
Wet Hours 1.5
[Mean rain rate: 2.2 mm/h]		17 hrs (88%) [4%] 3, 2009 0, 2010
Cloud Cover Overcast with periods of Mostly Cloudy
Events Thunder
Comments 1330, 15 Very Heavy Showers with Thunder; other 24hr Light/Moderate Showers
Extra Comments
Issues None known
Observer Absent? No
Pond Temperature (Heath) 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 17th July 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