Daily Report for 19th September 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 14.8 °C (+3.6) 23:57 14.0 °C (+2.1) 16.9 °C (+5.7), 2018 6.9 °C (-4.3), 2012
Maximum Temperature 20.1 °C (+1.7) 11:43 21.9 °C (+2.1) 24.7 °C (+6.3), 2024 14.7 °C (-3.7), 2017
Mean Temperature 17.0 °C (+2.7) 17.7 °C (+2.1) 19.0 °C, 2018 10.9 °C, 2017
Minimum Humidity 77% 11:29 65% 79%, 2023 38%, 2012
Maximum Humidity 92% 08:22 92% 96%, 2014 80%, 2010
Mean Humidity 87% 81% 88%, 2014 58%, 2012
Minimum Pressure 1013 hPa 04:24 1017 hPa 1030 hPa, 2019 1005 hPa, 2023
Maximum Pressure 1019 hPa 23:55 1021 hPa 1033 hPa, 2019 1010 hPa, 2023
Mean Pressure 1015 hPa 1019 hPa 1032 hPa, 2019 1007 hPa, 2023
Mean Wind Speed 1.0 mph (-2.9) 2.3 mph (-1.6) 9.8 mph, 2023 1.0 mph, 2021
Maximum Wind Speed 7.0 mph 16:10 8.8 mph 24.1 mph, 2018 6.0 mph, 2022
Maximum Gust 11.4 mph 16:15 13.9 mph 40.3 mph, 2018 8.1 mph, 2015
Mean Wind Direction NW
Rainfall 1.2 mm 25.9 mm (82%) 5.4 mm, 2014
Maximum Hourly Rain 1.2 mm 14:33 4.7 mm, 2014
Maximum 10-min Rain 0.5 mm 13:48 3.6 mm, 2014
Maximum Rain Rate 3.6 mm/h 13:58 66 mm/h, 2014
Minimum Dew Point 12.5 °C 23:57 11.8 °C 14.7 °C, 2014 1.5 °C, 2012
Maximum Dew Point 16.2 °C 11:37 16.3 °C 19.0 °C, 2014 6.2 °C, 2012
Mean Dew Point 14.8 °C 14.2 °C 16.3 °C, 2014 3.4 °C, 2012
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 15.4 °C * 07:16 14.2 °C 17.1 °C, 2018 6.9 °C, 2012
Day Maximum (09-21) 20.1 °C 11:43 21.9 °C 24.7 °C, 2024 14.7 °C, 2017
Max 10m Temp Rise 0.6 °C 10:23 0.6 °C 0.9 °C, 2019 0.4 °C, 2016
Max 1hr Temp Rise 2.6 °C 10:44 2.2 °C 4.6 °C, 2019 1.2 °C, 2010
Max 1hr Hum Rise 8% 13:48 8% 12%, 2013 5%, 2010
Max 10m Temp Fall 0.4 °C 12:51 0.4 °C 0.8 °C, 2012 0.2 °C, 2010
Max 1hr Temp Fall 1.4 °C 13:24 1.5 °C 2.7 °C, 2017 0.5 °C, 2023
Max 1hr Hum Fall 11% 10:26 9% 20%, 2019 4%, 2010
Max 10m Wind Speed 5.3 mph 16:17 6.4 mph 17.8 mph, 2018 3.6 mph, 2015
Minimum Feels-like 17.3 °C 23:56 16.5 °C 20.5 °C, 2018 4.7 °C, 2012
Maximum Feels-like 24.8 °C 11:43 26.4 °C 29.8 °C, 2024 15.6 °C, 2017
Mean Feels-like 20.8 °C 21.3 °C 23.3 °C, 2014 11.1 °C, 2017
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 5.3 °C (-1.8) 7.8 °C (+0.1) 13.0 °C (+5.9), 2019 4.9 °C (-2.2), 2018
Humidity Range 15% 27% 45%, 2020 9%, 2023
Pressure Range 6 hPa 4 hPa 9 hPa, 2011 2 hPa, 2016
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 1 [9%]81 hrs (85%) [36%] 11.3 [101%], 2019 0.1 [1%], 2023
Wet Hours 2
[Mean rain rate: 0.6 mm/h]
17 hrs (64%) [3.6%] 3, 2013 0, 2009
Cloud Cover am: Partly Cloudy transitioned to Partly Cloudy
pm: Overcast
Events None
Comments brief rn
Extra Comments dbl rainbow
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 18.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 19th September 2021.
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