Daily Report for 4th March 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 3.2 °C (+0.5) 08:29 3.4 °C (+0.7) 7.5 °C (+4.8), 2017 -1.0 °C (-3.7), 2010
Maximum Temperature 5.3 °C (-3.8) 00:11 6.9 °C (-2.1) 11.9 °C (+2.8), 2017 5.3 °C (-3.8), 2021
Mean Temperature 4.5 °C (-1.6) 4.9 °C (-0.7) 9.2 °C, 2017 2.9 °C, 2010
Minimum Humidity 74% 22:59 81% 82%, 2018 43%, 2015
Maximum Humidity 97% 03:40 96% 98%, 2014 81%, 2015
Mean Humidity 89% 90% 90%, 2018 62%, 2015
Minimum Pressure 1024 hPa 04:52 1028 hPa 1031 hPa, 2011 980 hPa, 2009
Maximum Pressure 1029 hPa 23:54 1032 hPa 1038 hPa, 2015 986 hPa, 2009
Mean Pressure 1026 hPa 1030 hPa 1033 hPa, 2011 983 hPa, 2009
Mean Wind Speed 4.1 mph (-1.1) 2.2 mph (-3.0) 8.4 mph, 2019 2.3 mph, 2014
Maximum Wind Speed 15.5 mph 20:40 9.8 mph 21.8 mph, 2019 10.0 mph, 2020
Maximum Gust 19.4 mph 20:40 14.0 mph 30.0 mph, 2019 13.8 mph, 2014
Mean Wind Direction NE
Rainfall 0.2 mm 6.7 mm (124%) 16.0 mm, 2009
Maximum Hourly Rain 0.2 mm 6.0 mm, 2009
Maximum 10-min Rain 0.2 mm 1.5 mm, 2012
Maximum Rain Rate n/a 18, 2020
Minimum Dew Point -0.6 °C 23:36 1.3 °C 1.8 °C, 2017 -5.1 °C, 2010
Maximum Dew Point 4.7 °C 00:11 5.0 °C 8.2 °C, 2012 0.6 °C, 2011
Mean Dew Point 2.8 °C 3.3 °C 4.4 °C, 2018 -1.9 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 3.2 °C 08:30 3.4 °C 7.8 °C, 2017 0.6 °C, 2011
Day Maximum (09-21) * 5.2 °C * 16:09 6.9 °C 11.9 °C, 2017 5.2 °C, 2021
Max 10m Temp Rise 0.2 °C 10:36 0.4 °C 0.7 °C, 2014 0.2 °C, 2021
Max 1hr Temp Rise 0.5 °C 10:02 0.9 °C 2.9 °C, 2014 0.5 °C, 2021
Max 1hr Hum Rise 3% 16:15 4% 17%, 2019 3%, 2018
Max 10m Temp Fall 0.4 °C 20:37 0.3 °C 1.8 °C, 2019 0.2 °C, 2018
Max 1hr Temp Fall 0.7 °C 20:50 1.1 °C 4.8 °C, 2012 0.7 °C, 2021
Max 1hr Hum Fall 8% 21:49 5% 13%, 2019 7%, 2018
Max 10m Wind Speed 9.5 mph 19:42 6.2 mph 16.0 mph, 2019 6.6 mph, 2020
Minimum Feels-like -1.0 °C 08:51 -0.2 °C 3.4 °C, 2017 -4.5 °C, 2011
Maximum Feels-like 5.3 °C 00:00 6.9 °C 11.9 °C, 2017 5.3 °C, 2021
Mean Feels-like 1.9 °C 3.4 °C 7.8 °C, 2017 0.5 °C, 2010
Air-frost Hrs 0 hrs 0 hrs 1 hrs, 2010 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 2.1 °C (-4.3) 3.6 °C (-2.8) 8.5 °C (+2.1), 2010 2.1 °C (-4.3), 2021
Humidity Range 23% 14% 46%, 2009 14%, 2018
Pressure Range 5 hPa 4 hPa 17 hPa, 2015 3 hPa, 2018
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]7.9 hrs (62%) [20%] 8 [81%], 2013 0 [0%], 2012
Wet Hours 15 hrs (73%) [5.2%] 14, 2012 , 2009
Cloud Cover Overcast
Events None
Comments dense fog and dz til 7
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 4.5 °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

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Webcam Summary of Cloud Conditions

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