Daily Report for 18th April 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 0.4 °C (-5.6) 06:19 2.1 °C (-3.6) 12.3 °C (+6.3), 2018 0.4 °C (-5.6), 2021
Maximum Temperature 14.6 °C (+0.1) 16:51 10.8 °C (-3.0) 24.9 °C (+10.4), 2018 10.8 °C (-3.7), 2023
Mean Temperature 8.7 °C (-2.8) 6.5 °C (-3.3) 18.3 °C, 2018 8.2 °C, 2012
Minimum Humidity 32% 15:26 47% 70%, 2020 28%, 2018
Maximum Humidity 87% 06:47 84% 97%, 2009 70%, 2013
Mean Humidity 57% 67% 81%, 2012 54%, 2017
Minimum Pressure 1024 hPa 16:53 1023 hPa 1027 hPa, 2023 977 hPa, 2012
Maximum Pressure 1028 hPa 00:02 1029 hPa 1032 hPa, 2017 992 hPa, 2012
Mean Pressure 1026 hPa 1026 hPa 1029 hPa, 2017 984 hPa, 2012
Mean Wind Speed 0.9 mph (-4.0) 4.0 mph (-0.9) 10.6 mph, 2013 0.9 mph, 2021
Maximum Wind Speed 9.0 mph 12:54 12.7 mph 20.8 mph, 2013 7.1 mph, 2010
Maximum Gust 12.5 mph 12:55 18.9 mph 30.1 mph, 2013 10.0 mph, 2010
Mean Wind Direction NE
Rainfall 0.0 mm 0.9 mm (4%) 3.4 mm, 2012
Maximum Hourly Rain n/a 1.3, 2020
Maximum 10-min Rain n/a 0.6, 2012
Maximum Rain Rate n/a 5, 2012
Minimum Dew Point -3.2 °C 12:31 -2.4 °C 5.0 °C, 2018 -3.2 °C, 2021
Maximum Dew Point 3.3 °C 23:51 3.3 °C 13.4 °C, 2018 1.3 °C, 2017
Mean Dew Point -0.1 °C 0.5 °C 10.4 °C, 2018 -0.8 °C, 2017
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 0.4 °C 06:22 2.5 °C 12.3 °C, 2018 0.4 °C, 2021
Day Maximum (09-21) 14.6 °C 17:02 10.6 °C 24.9 °C, 2018 10.8 °C, 2023
Max 10m Temp Rise 1.1 °C 07:31 0.7 °C 1.2 °C, 2009 0.4 °C, 2020
Max 1hr Temp Rise 4.7 °C 07:45 2.4 °C 4.7 °C, 2021 1.5 °C, 2020
Max 1hr Hum Rise 13% 21:14 12% 24%, 2013 4%, 2016
Max 10m Temp Fall 0.6 °C 20:30 0.6 °C 2.5 °C, 2013 0.3 °C, 2023
Max 1hr Temp Fall 2.9 °C 20:36 2.0 °C 4.3 °C, 2013 1.0 °C, 2023
Max 1hr Hum Fall 19% 08:28 12% 19%, 2021 6%, 2020
Max 10m Wind Speed 4.7 mph 11:46 9.2 mph 14.9 mph, 2013 4.7 mph, 2021
Minimum Feels-like 0.4 °C 06:18 -1.0 °C 13.4 °C, 2018 -0.3 °C, 2024
Maximum Feels-like 14.6 °C 16:45 10.3 °C 26.6 °C, 2018 10.8 °C, 2023
Mean Feels-like 8.7 °C 5.0 °C 19.8 °C, 2018 6.3 °C, 2012
Air-frost Hrs 0 hrs 0.8 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 14.2 °C (+5.8) 8.7 °C (+0.6) 16.0 °C (+7.6), 2010 4.1 °C (-4.3), 2023
Humidity Range 55% 37% 56%, 2018 19%, 2023
Pressure Range 4 hPa 6 hPa 15 hPa, 2012 2 hPa, 2022
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 12.5 [99%]98 hrs (104%) [45%] 12.7 [100%], 2018 0.5 [4%], 2020
Wet Hours 02.5 hrs (9%) [0.6%] 4, 2012 0, 2009
Cloud Cover Sunny
Events Maximum possible sunshine
Comments -
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 9.5 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 18th 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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