Daily Report for 20th April 2012

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 5.1 °C (-1.1) 06:26 3.8 °C (-2.0) 13.9 °C (+7.7), 2018 1.4 °C (-4.8), 2013
Maximum Temperature 13.0 °C (-1.8) 11:14 12.2 °C (-1.9) 25.9 °C (+11.1), 2018 10.6 °C (-4.2), 2024
Mean Temperature 8.3 °C (-1.4) 8.0 °C (-1.9) 20.0 °C, 2018 7.2 °C, 2024
Minimum Humidity 54% 12:11 49% 75%, 2014 33%, 2011
Maximum Humidity 94% 07:03 89% 95%, 2014 72%, 2017
Mean Humidity 80% 70% 90%, 2014 54%, 2011
Minimum Pressure 990 hPa 00:48 1001 hPa 1032 hPa, 2017 990 hPa, 2012
Maximum Pressure 995 hPa 18:51 1010 hPa 1037 hPa, 2017 995 hPa, 2012
Mean Pressure 992 hPa 1006 hPa 1035 hPa, 2017 992 hPa, 2012
Mean Wind Speed 4.6 mph (-0.3) 4.7 mph (-0.2) 7.9 mph, 2020 1.0 mph, 2021
Maximum Wind Speed 15.6 mph 13.5 mph 18.4 mph, 2020 8.9 mph, 2021
Maximum Gust 25.6 mph 17:38 19.1 mph 28.8 mph, 2023 11.4 mph, 2021
Mean Wind Direction WSW
Rainfall 8.0 mm 44.5 mm (159%) 8.0 mm, 2012
Maximum Hourly Rain 4.9 mm 14:37 4.9 mm, 2012
Maximum 10-min Rain 2.6 mm 13:45 2.6 mm, 2012
Maximum Rain Rate 30 mm/h 13:46 30 mm/h, 2012
Minimum Dew Point 3.0 °C 17:47 -0.7 °C 9.6 °C, 2018 -3.0 °C, 2010
Maximum Dew Point 7.2 °C 09:47 5.9 °C 14.1 °C, 2018 4.2 °C, 2013
Mean Dew Point 4.9 °C 2.5 °C 11.5 °C, 2018 -0.1 °C, 2013
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 5.1 °C 06:25 4.1 °C 13.9 °C, 2018 1.4 °C, 2013
Day Maximum (09-21) 13.0 °C 11:13 12.2 °C 25.9 °C, 2018 10.6 °C, 2024
Max 10m Temp Rise 0.8 °C 08:13 0.7 °C 1.0 °C, 2013 0.4 °C, 2014
Max 1hr Temp Rise 2.7 °C 08:57 2.7 °C 4.2 °C, 2013 1.6 °C, 2014
Max 1hr Hum Rise 19% 18:40 12% 29%, 2023 4%, 2010
Max 10m Temp Fall 1.7 °C 17:49 0.8 °C 1.7 °C, 2012 0.4 °C, 2014
Max 1hr Temp Fall 3.6 °C 13:50 2.2 °C 4.3 °C, 2023 1.3 °C, 2017
Max 1hr Hum Fall 13% 11:26 14% 19%, 2013 1%, 2017
Max 10m Wind Speed 9.3 mph 17:49 9.1 mph 14.5 mph, 2023 5.7 mph, 2021
Minimum Feels-like 2.5 °C 06:44 1.3 °C 15.1 °C, 2018 -0.6 °C, 2024
Maximum Feels-like 13.0 °C 11:07 12.2 °C 28.6 °C, 2018 10.6 °C, 2024
Mean Feels-like 7.2 °C 6.9 °C 22.0 °C, 2018 5.4 °C, 2024
Air-frost Hrs 0 hrs 0.3 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 7.9 °C (-0.7) 8.3 °C (+0.1) 15.3 °C (+6.7), 2011 6.7 °C (-1.9), 2014
Humidity Range 40% 40% 56%, 2013 20%, 2014
Pressure Range 5 hPa 9 hPa 11 hPa, 2014 2 hPa, 2011
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 5 [39%]84 hrs (79%) [34%] 13 [101%], 2019 0 [0%], 2014
Wet Hours 2
[Mean rain rate: 4.0 mm/h]
48 hrs (157%) [10%] 5, 2014 0, 2009
Cloud Cover am: Mostly Sunny with periods of Partly Cloudy
pm: Mostly Cloudy with periods of Overcast
Events Hail: small stones
Light Thunderstorm
Comments 13 Light Hail ; 1330 Thunderstorm ; 14, 18 Heavy Showers
Extra Comments Detail: 5x IC, 2 with overhead thunder.
Issues None known
Observer Absent? No
Pond Temperature (Heath) 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 20th April 2012.
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