Daily Report for 20th April 2009

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 4.1 °C (-0.9) 06:55 6.9 °C (+2.1) 13.9 °C (+8.9), 2018 1.4 °C (-3.6), 2013
Maximum Temperature 19.0 °C (+6.0) 15:42 15.5 °C (+3.3) 25.9 °C (+12.9), 2018 13.0 °C (-0.0), 2012
Mean Temperature 10.9 °C (+2.6) 10.7 °C (+2.7) 20.0 °C, 2018 7.8 °C, 2013
Minimum Humidity 46% 17:26 60% 75%, 2014 33%, 2011
Maximum Humidity 93% 08:47 93% 95%, 2014 72%, 2017
Mean Humidity 72% 79% 90%, 2014 54%, 2011
Minimum Pressure 1026 hPa 11:42 1011 hPa 1032 hPa, 2017 990 hPa, 2012
Maximum Pressure 1028 hPa 08:17 1016 hPa 1037 hPa, 2017 995 hPa, 2012
Mean Pressure 1027 hPa 1013 hPa 1035 hPa, 2017 992 hPa, 2012
Mean Wind Speed n/a (-4.9) 0.0 mph (-4.9) 7.9, 2020 2.3, 2011
Maximum Wind Speed n/a 0.0 mph 18.4, 2020 9.1, 2018
Maximum Gust n/a 0.0 mph 27.6, 2020 12.7, 2018
Mean Wind Direction n/a
Rainfall 0.0 mm 27.4 mm (93%) 8.0 mm, 2012
Maximum Hourly Rain n/a 4.9, 2012
Maximum 10-min Rain n/a 2.6, 2012
Maximum Rain Rate n/a 30, 2012
Minimum Dew Point 2.5 °C 06:01 3.9 °C 9.6 °C, 2018 -3.0 °C, 2010
Maximum Dew Point 10.0 °C 13:17 9.6 °C 14.1 °C, 2018 4.2 °C, 2013
Mean Dew Point 5.5 °C 6.7 °C 11.5 °C, 2018 -0.1 °C, 2013
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 4.1 °C 7.1 °C 13.9 °C, 2018 1.4 °C, 2013
Day Maximum (09-21) 19.0 °C 15.5 °C 25.9 °C, 2018 13.0 °C, 2012
Max 10m Temp Rise 0.8 °C 13:22 0.4 °C 1.0 °C, 2013 0.4 °C, 2014
Max 1hr Temp Rise 3.3 °C 13:24 1.2 °C 4.2 °C, 2013 1.6 °C, 2014
Max 1hr Hum Rise 8% 21:34 3% 19%, 2012 4%, 2010
Max 10m Temp Fall 0.9 °C 22:46 0.3 °C 1.7 °C, 2012 0.4 °C, 2014
Max 1hr Temp Fall 2.1 °C 20:41 0.8 °C 3.6 °C, 2012 1.3 °C, 2017
Max 1hr Hum Fall 13% 14:20 4% 19%, 2013 1%, 2017
Max 10m Wind Speed n/a 0.0 mph 14.4, 2020 6.8, 2018
Minimum Feels-like n/a 0.0 °C 15.1, 2018 0.1, 2013
Maximum Feels-like n/a 0.0 °C 28.6, 2018 13.0, 2012
Mean Feels-like n/a 0.0 °C 22, 2018 7.2, 2012
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 14.9 °C (+6.9) 8.6 °C (+1.1) 15.3 °C (+7.3), 2011 6.7 °C (-1.3), 2014
Humidity Range 47% 33% 56%, 2013 20%, 2014
Pressure Range 2 hPa 6 hPa 11 hPa, 2014 2 hPa, 2011
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 10 [78%]102 hrs (106%) [42%] 13 [102%], 2019 0 [0%], 2014
Wet Hours 033 hrs (108%) [6.9%] 5, 2014 0, 2009
Cloud Cover not available
Events None
Comments -
Extra Comments
Issues None known
Observer Absent? No
Pond Temperature (Heath) 0.0 °C
Notes
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 initially pulled from the official weather station at Heathrow, and later adjusted by hand to reflect local conditions based on webcam observations. Wet hrs are dervied algorithmically from rainfall data, though may be adjusted manually. Cloud cover and Events are manually reported, often with multi-week delays.
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Daily Graph of Conditions

daygraph daygraph 2 daygraph-wdir

Webcam Summary of Cloud Conditions


Webcam summary not available for this day

Wind rose