Daily Report for 17th January 2021

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 3.2 °C (+0.8) 23:57 0.5 °C (-2.0) 6.6 °C (+4.2), 2014 -5.5 °C (-7.9), 2013
Maximum Temperature 7.1 °C (+0.1) 12:35 5.4 °C (-1.6) 10.6 °C (+3.6), 2020 2.3 °C (-4.7), 2013
Mean Temperature 5.4 °C (+0.5) 3.0 °C (-1.8) 7.6 °C, 2011 -1.1 °C, 2013
Minimum Humidity 77% 15:10 84% 85%, 2011 49%, 2009
Maximum Humidity 91% 23:38 94% 98%, 2010 84%, 2017
Mean Humidity 84% 90% 93%, 2011 68%, 2009
Minimum Pressure 1019 hPa 02:23 1017 hPa 1033 hPa, 2017 987 hPa, 2014
Maximum Pressure 1028 hPa 21:12 1024 hPa 1038 hPa, 2017 993 hPa, 2014
Mean Pressure 1024 hPa 1020 hPa 1036 hPa, 2017 990 hPa, 2014
Mean Wind Speed 5.5 mph (+0.3) 3.7 mph (-1.5) 10.1 mph, 2018 0.5 mph, 2017
Maximum Wind Speed 14.4 mph 06:20 10.9 mph 22.1 mph, 2020 5.8 mph, 2017
Maximum Gust 19.4 mph 06:21 17.2 mph 34.6 mph, 2018 8.4 mph, 2017
Mean Wind Direction NW
Rainfall 0.0 mm 42.3 mm (140%) 16.1 mm, 2011
Maximum Hourly Rain n/a 5, 2009
Maximum 10-min Rain n/a 1.1, 2011
Maximum Rain Rate n/a 15, 2011
Minimum Dew Point 1.7 °C 23:57 -0.9 °C 5.3 °C, 2014 -6.7 °C, 2013
Maximum Dew Point 4.6 °C 00:00 3.8 °C 9.4 °C, 2020 -0.5 °C, 2013
Mean Dew Point 2.9 °C 1.6 °C 6.5 °C, 2011 -3.1 °C, 2013
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 4.2 °C * 08:07 1.4 °C 8.6 °C, 2011 -5.5 °C, 2013
Day Maximum (09-21) 7.1 °C 13:18 5.1 °C 9.0 °C, 2009 2.3 °C, 2013
Max 10m Temp Rise 0.4 °C 10:20 0.3 °C 0.6 °C, 2010 0.1 °C, 2011
Max 1hr Temp Rise 1.2 °C 11:09 1.0 °C 2.4 °C, 2013 0.4 °C, 2011
Max 1hr Hum Rise 3% 18:03 4% 7%, 2018 2%, 2016
Max 10m Temp Fall 0.3 °C 07:18 0.4 °C 0.9 °C, 2019 0.1 °C, 2016
Max 1hr Temp Fall 0.8 °C 18:03 1.2 °C 2.0 °C, 2017 0.3 °C, 2016
Max 1hr Hum Fall 5% 12:43 4% 13%, 2017 3%, 2016
Max 10m Wind Speed 11.3 mph 11:21 8.8 mph 17.1 mph, 2020 4.4 mph, 2017
Minimum Feels-like -0.4 °C 08:00 -3.8 °C 2.8 °C, 2011 -5.5 °C, 2013
Maximum Feels-like 6.6 °C 16:49 5.0 °C 11.6 °C, 2020 2.3 °C, 2013
Mean Feels-like 2.8 °C 0.8 °C 6.7 °C, 2011 -1.9 °C, 2013
Air-frost Hrs 0 hrs 3 hrs 12 hrs, 2013 0 hrs, 2010
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 3.9 °C (-0.7) 4.9 °C (+0.4) 8.5 °C (+3.9), 2012 1.9 °C (-2.7), 2014
Humidity Range 14% 10% 39%, 2009 12%, 2011
Pressure Range 8 hPa 6 hPa 19 hPa, 2010 2 hPa, 2012
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 3.5 [47%]22 hrs (68%) [17%] 7 [93%], 2017 0.1 [1%], 2011
Wet Hours 047 hrs (127%) [11%] 8, 2011 , 2009
Cloud Cover am: Mostly Sunny
pm: Hazy
Events None
Comments -
Extra Comments
Issues no pond temp due to lockdown
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

day graph

Webcam Summary of Cloud Conditions

daycamsumFull resolution individual images at up-to 5 minute intervals

Wind rose