Daily Report for 9th January 2020

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 5.8 °C (+3.4) 23:55 5.7 °C (+3.2) 8.4 °C (+6.0), 2015 -4.2 °C (-6.6), 2010
Maximum Temperature 12.7 °C (+5.7) 13:41 10.1 °C (+3.1) 14.8 °C (+7.8), 2015 0.6 °C (-6.4), 2010
Mean Temperature 11.1 °C (+4.5) 8.3 °C (+3.1) 11.9 °C, 2015 -1.9 °C, 2010
Minimum Humidity 75% 13:04 78% 88%, 2018 64%, 2014
Maximum Humidity 94% 01:06 93% 98%, 2013 84%, 2017
Mean Humidity 87% 87% 93%, 2021 78%, 2014
Minimum Pressure 1004 hPa 16:39 1019 hPa 1028 hPa, 2019 982 hPa, 2016
Maximum Pressure 1015 hPa 00:00 1029 hPa 1033 hPa, 2012 997 hPa, 2016
Mean Pressure 1008 hPa 1024 hPa 1030 hPa, 2012 989 hPa, 2016
Mean Wind Speed 8.9 mph (+3.7) 6.2 mph (+1.0) 11.1 mph, 2015 1.0 mph, 2021
Maximum Wind Speed 20.5 mph 08:00 15.4 mph 28.4 mph, 2015 6.8 mph, 2021
Maximum Gust 33.4 mph 09:20 24.5 mph 38.9 mph, 2016 10.3 mph, 2021
Mean Wind Direction SW
Rainfall 6.4 mm 8.1 mm (51%) 6.4 mm, 2020
Maximum Hourly Rain 4.4 mm 15:58 4.4 mm, 2020
Maximum 10-min Rain 1.8 mm 15:58 1.8 mm, 2020
Maximum Rain Rate 14 mm/h 15:14 36 mm/h, 2017
Minimum Dew Point 4.3 °C 23:55 3.8 °C 6.1 °C, 2012 -5.4 °C, 2010
Maximum Dew Point 10.9 °C 05:12 8.4 °C 13.2 °C, 2015 -2.3 °C, 2010
Mean Dew Point 8.9 °C 6.2 °C 8.9 °C, 2020 -4.1 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 9.9 °C * 23:25 6.9 °C 9.9 °C, 2020 -4.2 °C, 2010
Day Maximum (09-21) 12.7 °C 13:39 9.9 °C 14.8 °C, 2015 0.6 °C, 2010
Max 10m Temp Rise 0.3 °C 00:32 0.3 °C 0.8 °C, 2010 0.2 °C, 2012
Max 1hr Temp Rise 0.9 °C 01:02 0.8 °C 1.4 °C, 2011 0.4 °C, 2018
Max 1hr Hum Rise 8% 15:00 5% 13%, 2015 3%, 2012
Max 10m Temp Fall 0.7 °C 23:14 0.4 °C 1.2 °C, 2016 0.1 °C, 2018
Max 1hr Temp Fall 1.6 °C 23:29 0.9 °C 2.8 °C, 2016 0.2 °C, 2018
Max 1hr Hum Fall 6% 08:04 6% 15%, 2014 1%, 2018
Max 10m Wind Speed 16.7 mph 08:03 11.7 mph 20.4 mph, 2015 4.9 mph, 2021
Minimum Feels-like 2.4 °C 23:45 1.9 °C 5.8 °C, 2012 -9.8 °C, 2010
Maximum Feels-like 14.1 °C 04:52 10.7 °C 17.4 °C, 2015 -3.3 °C, 2010
Mean Feels-like 11.3 °C 7.0 °C 12.2 °C, 2015 -6.7 °C, 2010
Air-frost Hrs 0 hrs 0 hrs 22 hrs, 2010 0 hrs, 2011
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 6.9 °C (+2.3) 4.4 °C (-0.2) 8.4 °C (+3.8), 2013 3.5 °C (-1.1), 2018
Humidity Range 19% 14% 32%, 2014 6%, 2017
Pressure Range 12 hPa 10 hPa 20 hPa, 2017 2 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 3.5 [48%]13 hrs (75%) [19%] 7.3 [101%], 2011 0 [0%], 2018
Wet Hours 4
[Mean rain rate: 1.6 mm/h]
9 hrs (46%) [4.2%] 8, 2017 , 2009
Cloud Cover am: Partly Cloudy transitioned to Sunny
pm: Sunny transitioned to Overcast
Events None
Comments Rain spells
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 6.5 °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

daycamsumFull resolution individual images at up-to 5 minute intervals

Wind rose