Daily Report for 23rd April 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 1.7 °C (-4.7) 06:12 2.3 °C (-3.5) 11.7 °C (+5.3), 2019 1.7 °C (-4.7), 2021
Maximum Temperature 15.1 °C (+0.0) 15:05 11.7 °C (-2.4) 26.5 °C (+11.4), 2011 9.8 °C (-5.2), 2016
Mean Temperature 8.9 °C (-2.3) 7.1 °C (-3.0) 18.6 °C, 2011 6.7 °C, 2016
Minimum Humidity 23% 16:09 46% 68%, 2024 23%, 2021
Maximum Humidity 92% 06:47 86% 95%, 2012 68%, 2017
Mean Humidity 63% 67% 84%, 2023 52%, 2011
Minimum Pressure 1029 hPa 17:01 1023 hPa 1029 hPa, 2021 990 hPa, 2012
Maximum Pressure 1031 hPa 09:18 1028 hPa 1031 hPa, 2021 1002 hPa, 2012
Mean Pressure 1030 hPa 1026 hPa 1030 hPa, 2021 996 hPa, 2012
Mean Wind Speed 3.0 mph (-1.9) 3.6 mph (-1.3) 7.8 mph, 2018 1.7 mph, 2011
Maximum Wind Speed 11.5 mph 15:29 12.2 mph 21.5 mph, 2012 7.6 mph, 2010
Maximum Gust 18.2 mph 16:20 18.0 mph 28.5 mph, 2022 10.7 mph, 2015
Mean Wind Direction SE
Rainfall 0.0 mm 0.9 mm (3%) 4.1 mm, 2023
Maximum Hourly Rain n/a 3.1, 2023
Maximum 10-min Rain n/a 2.4, 2023
Maximum Rain Rate n/a 30, 2023
Minimum Dew Point -6.3 °C 16:09 -2.1 °C 6.7 °C, 2019 -6.3 °C, 2021
Maximum Dew Point 5.0 °C 09:41 3.9 °C 11.6 °C, 2019 3.5 °C, 2010
Mean Dew Point 1.2 °C 1.1 °C 8.2 °C, 2019 0.1 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 1.7 °C 06:12 2.6 °C 11.7 °C, 2019 1.7 °C, 2021
Day Maximum (09-21) 15.1 °C 15:05 11.6 °C 26.5 °C, 2011 9.8 °C, 2016
Max 10m Temp Rise 0.8 °C 06:53 0.7 °C 1.4 °C, 2011 0.5 °C, 2013
Max 1hr Temp Rise 3.0 °C 07:33 2.5 °C 4.9 °C, 2011 1.5 °C, 2022
Max 1hr Hum Rise 12% 17:17 11% 14%, 2012 5%, 2009
Max 10m Temp Fall 0.5 °C 19:48 0.6 °C 1.2 °C, 2009 0.4 °C, 2013
Max 1hr Temp Fall 2.0 °C 20:16 2.0 °C 2.7 °C, 2009 1.3 °C, 2018
Max 1hr Hum Fall 20% 10:10 13% 20%, 2021 5%, 2017
Max 10m Wind Speed 9.8 mph 15:06 8.8 mph 12.3 mph, 2018 7.4 mph, 2020
Minimum Feels-like 1.7 °C 05:57 -0.4 °C 11.8 °C, 2019 -0.9 °C, 2016
Maximum Feels-like 15.1 °C 15:04 11.3 °C 26.9 °C, 2011 9.5 °C, 2016
Mean Feels-like 8.7 °C 5.9 °C 19.0 °C, 2011 4.9 °C, 2016
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 13.4 °C (+4.7) 9.4 °C (+1.2) 16.4 °C (+7.7), 2011 3.9 °C (-4.8), 2012
Humidity Range 69% 39% 69%, 2021 24%, 2024
Pressure Range 3 hPa 5 hPa 12 hPa, 2012 2 hPa, 2010
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 12 [93%]148 hrs (121%) [52%] 13 [100%], 2010 0 [0%], 2019
Wet Hours 02.5 hrs (7%) [0.5%] 7, 2012 0, 2009
Cloud Cover Sunny
Events None
Comments -
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 10.5 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 23rd 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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Webcam Summary of Cloud Conditions

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