Daily Report for 12th September 2017

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 10.2 °C (-1.7) 06:55 11.1 °C (-1.2) 14.6 °C (+2.7), 2011 6.2 °C (-5.7), 2024
Maximum Temperature 18.2 °C (-1.4) 15:03 19.4 °C (-1.0) 25.8 °C (+6.2), 2022 14.5 °C (-5.1), 2024
Mean Temperature 13.7 °C (-1.6) 15.2 °C (-1.1) 20.3 °C, 2022 10.0 °C, 2024
Minimum Humidity 49% 15:08 58% 72%, 2013 48%, 2011
Maximum Humidity 93% 23:41 91% 97%, 2013 83%, 2012
Mean Humidity 78% 77% 87%, 2018 65%, 2015
Minimum Pressure 995 hPa 23:45 1005 hPa 1028 hPa, 2009 995 hPa, 2017
Maximum Pressure 1007 hPa 13:31 1013 hPa 1034 hPa, 2009 1007 hPa, 2017
Mean Pressure 1004 hPa 1009 hPa 1031 hPa, 2009 1004 hPa, 2017
Mean Wind Speed 7.8 mph (+3.9) 5.0 mph (+1.1) 10.8 mph, 2011 0.8 mph, 2021
Maximum Wind Speed 19.9 mph 22:55 14.0 mph 22.1 mph, 2011 5.6 mph, 2021
Maximum Gust 30.0 mph 22:56 21.6 mph 37.4 mph, 2011 8.7 mph, 2013
Mean Wind Direction WSW
Rainfall 2.4 mm 26.6 mm (133%) 3.1 mm, 2018
Maximum Hourly Rain 1.3 mm 23:02 2.3 mm, 2012
Maximum 10-min Rain 0.7 mm 23:02 2.3 mm, 2012
Maximum Rain Rate 7 mm/h 23:02 60 mm/h, 2012
Minimum Dew Point 7.2 °C 15:00 8.5 °C 13.1 °C, 2022 2.6 °C, 2012
Maximum Dew Point 12.5 °C 23:57 13.5 °C 18.2 °C, 2022 10.0 °C, 2024
Mean Dew Point 9.7 °C 10.9 °C 16.3 °C, 2023 6.5 °C, 2024
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 10.2 °C 06:55 11.4 °C 17.7 °C, 2023 6.2 °C, 2024
Day Maximum (09-21) 18.2 °C 15:03 19.4 °C 25.8 °C, 2022 14.5 °C, 2024
Max 10m Temp Rise 0.6 °C 13:36 0.6 °C 0.9 °C, 2022 0.3 °C, 2018
Max 1hr Temp Rise 2.3 °C 08:56 2.0 °C 3.4 °C, 2012 1.1 °C, 2018
Max 1hr Hum Rise 14% 20:22 11% 14%, 2017 5%, 2011
Max 10m Temp Fall 0.4 °C 13:56 0.7 °C 1.2 °C, 2024 0.4 °C, 2010
Max 1hr Temp Fall 1.5 °C 20:54 1.7 °C 2.6 °C, 2012 1.0 °C, 2013
Max 1hr Hum Fall 9% 08:58 9% 16%, 2014 6%, 2013
Max 10m Wind Speed 14.0 mph 23:01 10.3 mph 14.8 mph, 2011 3.7 mph, 2021
Minimum Feels-like 10.9 °C 06:55 11.8 °C 17.5 °C, 2022 3.3 °C, 2024
Maximum Feels-like 18.7 °C 15:00 21.7 °C 31.8 °C, 2022 15.6 °C, 2024
Mean Feels-like 14.8 °C 16.9 °C 25.0 °C, 2022 9.2 °C, 2024
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 8.0 °C (+0.3) 8.2 °C (+0.1) 14.4 °C (+6.7), 2016 5.7 °C (-2.0), 2013
Humidity Range 44% 33% 44%, 2011 23%, 2018
Pressure Range 12 hPa 8 hPa 12 hPa, 2017 2 hPa, 2021
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 7.3 [63%]50 hrs (81%) [35%] 10 [86%], 2009 0.1 [1%], 2018
Wet Hours 3
[Mean rain rate: 0.8 mm/h]
28 hrs (168%) [9.5%] 6, 2018 0, 2009
Cloud Cover am: Sunny transitioned to Mostly Sunny
pm: Partly Cloudy or Mostly Cloudy
Events None
Comments 21- Rain
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 12th 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.
View monthly summary

Daily Graph of Conditions

day graph

Webcam Summary of Cloud Conditions

daycamsumLarge resolution version

Wind rose