Daily Report for 25th April 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 4.4 °C (-2.1) 06:05 2.5 °C (-3.4) 11.3 °C (+4.8), 2015 1.4 °C (-5.1), 2017
Maximum Temperature 12.8 °C (-2.5) 15:12 11.9 °C (-2.3) 22.4 °C (+7.1), 2013 10.7 °C (-4.6), 2023
Mean Temperature 8.2 °C (-2.3) 7.3 °C (-2.9) 16.4 °C, 2013 6.0 °C, 2017
Minimum Humidity 53% 14:37 46% 82%, 2014 33%, 2011
Maximum Humidity 88% 05:24 86% 97%, 2014 67%, 2017
Mean Humidity 71% 67% 93%, 2014 48%, 2017
Minimum Pressure 1027 hPa 19:09 1024 hPa 1027 hPa, 2021 982 hPa, 2012
Maximum Pressure 1031 hPa 10:19 1029 hPa 1031 hPa, 2021 998 hPa, 2012
Mean Pressure 1029 hPa 1026 hPa 1029 hPa, 2021 990 hPa, 2012
Mean Wind Speed 5.8 mph (+0.9) 3.7 mph (-1.2) 8.4 mph, 2018 3.0 mph, 2024
Maximum Wind Speed 14.1 mph 15:48 12.3 mph 25.6 mph, 2012 10.2 mph, 2014
Maximum Gust 21.7 mph 11:47 18.2 mph 45.3 mph, 2012 15.0 mph, 2023
Mean Wind Direction ENE
Rainfall 0.0 mm 0.9 mm (3%) 14.2 mm, 2012
Maximum Hourly Rain n/a 4.3, 2012
Maximum 10-min Rain n/a 2.2, 2022
Maximum Rain Rate n/a 40, 2012
Minimum Dew Point 0.6 °C 23:49 -1.9 °C 6.9 °C, 2014 -6.7 °C, 2017
Maximum Dew Point 4.6 °C 17:08 4.0 °C 12.5 °C, 2014 -1.2 °C, 2017
Mean Dew Point 3.0 °C 1.3 °C 9.5 °C, 2013 -4.4 °C, 2017
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 4.4 °C 06:03 2.7 °C 11.3 °C, 2015 1.4 °C, 2017
Day Maximum (09-21) 12.8 °C 15:12 11.8 °C 22.4 °C, 2013 10.7 °C, 2023
Max 10m Temp Rise 0.8 °C 11:59 0.7 °C 0.9 °C, 2019 0.2 °C, 2014
Max 1hr Temp Rise 1.7 °C 12:08 2.5 °C 2.7 °C, 2009 0.8 °C, 2014
Max 1hr Hum Rise 14% 20:28 12% 19%, 2022 4%, 2014
Max 10m Temp Fall 0.6 °C 20:18 0.6 °C 1.6 °C, 2022 0.4 °C, 2015
Max 1hr Temp Fall 2.2 °C 20:30 2.0 °C 3.8 °C, 2013 1.5 °C, 2009
Max 1hr Hum Fall 9% 09:32 13% 19%, 2019 2%, 2014
Max 10m Wind Speed 11.7 mph 16:04 8.9 mph 13.9 mph, 2018 7.5 mph, 2020
Minimum Feels-like 0.5 °C 05:54 -0.2 °C 12.5 °C, 2015 -2.9 °C, 2017
Maximum Feels-like 12.8 °C 15:09 11.5 °C 23.5 °C, 2013 10.7 °C, 2023
Mean Feels-like 6.5 °C 6.0 °C 17.5 °C, 2013 3.6 °C, 2017
Air-frost Hrs 0 hrs 0.6 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 8.4 °C (-0.4) 9.4 °C (+1.2) 11.6 °C (+2.8), 2013 4.5 °C (-4.3), 2014
Humidity Range 35% 39% 55%, 2013 15%, 2014
Pressure Range 4 hPa 5 hPa 16 hPa, 2012 3 hPa, 2011
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 11 [84%]172 hrs (129%) [55%] 13 [100%], 2011 0 [0%], 2014
Wet Hours 02.5 hrs (7%) [0.4%] 9, 2012 0, 2011
Cloud Cover Sunny with periods of Mostly Cloudy
Events None
Comments -
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 11.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 25th April 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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