Daily Report for 27th September 2017

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 13.3 °C (+2.8) 07:33 10.7 °C (-0.9) 13.7 °C (+3.2), 2023 5.8 °C (-4.7), 2024
Maximum Temperature 20.7 °C (+3.4) 15:16 18.5 °C (-0.7) 23.6 °C (+6.3), 2018 12.4 °C (-4.9), 2024
Mean Temperature 16.3 °C (+3.1) 14.4 °C (-0.8) 17.8 °C, 2023 10.4 °C, 2022
Minimum Humidity 64% 15:19 59% 80%, 2010 29%, 2018
Maximum Humidity 95% 05:14 92% 98%, 2010 81%, 2020
Mean Humidity 85% 79% 91%, 2010 62%, 2018
Minimum Pressure 1017 hPa 20:00 1010 hPa 1031 hPa, 2015 991 hPa, 2024
Maximum Pressure 1023 hPa 00:15 1016 hPa 1036 hPa, 2015 1005 hPa, 2022
Mean Pressure 1019 hPa 1013 hPa 1033 hPa, 2015 1002 hPa, 2024
Mean Wind Speed 4.1 mph (+0.2) 4.4 mph (+0.5) 7.1 mph, 2019 0.8 mph, 2014
Maximum Wind Speed 10.0 mph 14:00 12.5 mph 20.8 mph, 2016 4.9 mph, 2014
Maximum Gust 17.3 mph 16:43 19.3 mph 33.9 mph, 2016 7.8 mph, 2014
Mean Wind Direction SE
Rainfall 13.9 mm 48.9 mm (109%) 13.9 mm, 2017
Maximum Hourly Rain 4.8 mm 23:41 7.7 mm, 2024
Maximum 10-min Rain 1.3 mm 21:10 3.5 mm, 2019
Maximum Rain Rate 13 mm/h 21:03 92 mm/h, 2019
Minimum Dew Point 12.5 °C 07:33 8.3 °C 12.7 °C, 2023 3.8 °C, 2024
Maximum Dew Point 14.9 °C 12:30 12.9 °C 16.8 °C, 2023 8.9 °C, 2020
Mean Dew Point 13.6 °C 10.5 °C 14.9 °C, 2023 7.5 °C, 2020
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 13.3 °C 07:33 10.9 °C 16.1 °C, 2021 8.2 °C, 2022
Day Maximum (09-21) 20.7 °C 15:16 18.5 °C 23.6 °C, 2018 12.4 °C, 2024
Max 10m Temp Rise 0.5 °C 12:04 0.6 °C 0.8 °C, 2018 0.3 °C, 2011
Max 1hr Temp Rise 1.6 °C 12:35 2.0 °C 3.3 °C, 2018 1.2 °C, 2024
Max 1hr Hum Rise 11% 20:24 11% 17%, 2012 2%, 2020
Max 10m Temp Fall 0.3 °C 15:30 0.6 °C 1.2 °C, 2021 0.1 °C, 2010
Max 1hr Temp Fall 1.2 °C 20:49 1.7 °C 3.1 °C, 2018 0.4 °C, 2010
Max 1hr Hum Fall 9% 12:55 11% 19%, 2018 4%, 2020
Max 10m Wind Speed 7.7 mph 16:44 9.2 mph 14.5 mph, 2016 3.7 mph, 2014
Minimum Feels-like 15.8 °C 07:19 10.9 °C 16.4 °C, 2023 3.4 °C, 2024
Maximum Feels-like 24.2 °C 15:10 20.5 °C 26.2 °C, 2023 13.9 °C, 2022
Mean Feels-like 19.4 °C 15.9 °C 21.7 °C, 2023 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 7.4 °C (+0.6) 7.8 °C (+0.3) 13.3 °C (+6.5), 2018 3.1 °C (-3.7), 2020
Humidity Range 31% 33% 61%, 2018 7%, 2020
Pressure Range 6 hPa 6 hPa 27 hPa, 2024 2 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 1 [9%]108 hrs (81%) [35%] 10.8 [101%], 2018 0 [0%], 2020
Wet Hours 4
[Mean rain rate: 3.5 mm/h]
43 hrs (115%) [6.6%] 5, 2024 0, 2009
Cloud Cover Overcast or Hazy
Events None
Comments 20- 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 27th 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