Daily Report for 17th September 2017

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 8.8 °C (-2.6) 01:49 10.4 °C (-1.7) 17.3 °C (+5.9), 2018 5.0 °C (-6.4), 2022
Maximum Temperature 16.5 °C (-2.2) 15:57 18.5 °C (-1.5) 24.8 °C (+6.1), 2018 13.4 °C (-5.3), 2013
Mean Temperature 11.9 °C (-2.4) 14.3 °C (-1.6) 20.3 °C, 2018 11.0 °C, 2022
Minimum Humidity 60% 16:18 58% 80%, 2023 36%, 2018
Maximum Humidity 95% 04:04 91% 95%, 2013 84%, 2009
Mean Humidity 84% 78% 89%, 2023 65%, 2012
Minimum Pressure 1012 hPa 03:45 1005 hPa 1027 hPa, 2020 987 hPa, 2015
Maximum Pressure 1016 hPa 22:45 1013 hPa 1031 hPa, 2020 1005 hPa, 2013
Mean Pressure 1013 hPa 1009 hPa 1029 hPa, 2020 999 hPa, 2015
Mean Wind Speed 2.2 mph (-1.7) 4.9 mph (+1.0) 8.3 mph, 2016 2.2 mph, 2017
Maximum Wind Speed 8.6 mph 16:52 13.6 mph 20.5 mph, 2016 8.1 mph, 2014
Maximum Gust 15.0 mph 16:48 21.3 mph 30.6 mph, 2016 12.5 mph, 2014
Mean Wind Direction N
Rainfall 0.0 mm 29.9 mm (106%) 5.5 mm, 2013
Maximum Hourly Rain n/a 2.6, 2023
Maximum 10-min Rain n/a 2.2, 2023
Maximum Rain Rate n/a 30, 2023
Minimum Dew Point 7.5 °C 00:53 7.9 °C 13.9 °C, 2014 2.0 °C, 2022
Maximum Dew Point 11.0 °C 13:49 12.8 °C 17.7 °C, 2023 5.0 °C, 2022
Mean Dew Point 9.2 °C 10.2 °C 16.1 °C, 2023 3.6 °C, 2022
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 8.8 °C 01:49 10.6 °C 17.3 °C, 2018 5.0 °C, 2022
Day Maximum (09-21) 16.5 °C 15:57 18.5 °C 24.8 °C, 2018 13.4 °C, 2013
Max 10m Temp Rise 0.5 °C 12:28 0.6 °C 0.7 °C, 2013 0.3 °C, 2016
Max 1hr Temp Rise 1.5 °C 12:51 2.0 °C 2.8 °C, 2010 0.8 °C, 2016
Max 1hr Hum Rise 11% 17:37 12% 15%, 2020 4%, 2014
Max 10m Temp Fall 0.5 °C 17:05 0.7 °C 0.5 °C, 2010 0.2 °C, 2014
Max 1hr Temp Fall 1.8 °C 17:48 1.8 °C 2.6 °C, 2010 0.8 °C, 2014
Max 1hr Hum Fall 12% 16:00 10% 26%, 2012 2%, 2016
Max 10m Wind Speed 6.7 mph 16:55 10.1 mph 14.0 mph, 2016 6.0 mph, 2019
Minimum Feels-like 7.4 °C 02:03 10.3 °C 20.3 °C, 2018 4.0 °C, 2022
Maximum Feels-like 18.0 °C 15:10 20.4 °C 27.5 °C, 2018 15.4 °C, 2010
Mean Feels-like 12.6 °C 15.6 °C 23.3 °C, 2018 10.0 °C, 2022
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 7.7 °C (+0.4) 8.1 °C (+0.2) 12.0 °C (+4.7), 2022 3.9 °C (-3.4), 2014
Humidity Range 35% 33% 52%, 2018 10%, 2016
Pressure Range 4 hPa 8 hPa 20 hPa, 2015 2 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 3 [26%]73 hrs (85%) [36%] 11.4 [100%], 2019 0 [0%], 2016
Wet Hours 030 hrs (127%) [7.2%] 5, 2013 0, 2009
Cloud Cover am: Overcast
pm: Partly Cloudy
Events None
Comments -
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 17th September 2017.
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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Wind rose