Daily Report for 17th April 2018

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 10.4 °C (+5.5) 06:33 7.3 °C (+2.5) 10.4 °C (+5.5), 2018 -0.3 °C (-5.2), 2021
Maximum Temperature 19.3 °C (+6.6) 13:38 13.2 °C (+1.1) 19.3 °C (+6.6), 2018 10.8 °C (-1.9), 2009
Mean Temperature 14.7 °C (+6.0) 10.0 °C (+1.8) 14.7 °C, 2018 6.7 °C, 2016
Minimum Humidity 44% 11:49 68% 94%, 2009 34%, 2010
Maximum Humidity 72% 03:34 90% 97%, 2009 66%, 2014
Mean Humidity 63% 82% 96%, 2009 54%, 2014
Minimum Pressure 1018 hPa 04:31 1004 hPa 1027 hPa, 2021 993 hPa, 2012
Maximum Pressure 1026 hPa 23:56 1012 hPa 1032 hPa, 2021 1014 hPa, 2009
Mean Pressure 1021 hPa 1008 hPa 1030 hPa, 2021 1006 hPa, 2012
Mean Wind Speed 9.0 mph (+4.1) 5.2 mph (+0.3) 9.0 mph, 2018 1.6 mph, 2021
Maximum Wind Speed 19.6 mph 12:44 13.6 mph 22.3 mph, 2012 6.8 mph, 2010
Maximum Gust 33.4 mph 15:02 21.4 mph 33.5 mph, 2012 9.5 mph, 2010
Mean Wind Direction SSW
Rainfall 0.0 mm 38.4 mm (154%) 7.7 mm, 2009
Maximum Hourly Rain n/a 2.7, 2009
Maximum 10-min Rain n/a 1.4, 2009
Maximum Rain Rate n/a 32.8, 2009
Minimum Dew Point 4.5 °C 00:43 4.7 °C 7.0 °C, 2009 -3.9 °C, 2016
Maximum Dew Point 10.7 °C 21:21 8.8 °C 11.2 °C, 2013 1.2 °C, 2021
Mean Dew Point 7.6 °C 6.8 °C 8.4 °C, 2009 -1.0 °C, 2016
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 10.4 °C 06:33 7.4 °C 10.4 °C, 2018 -0.3 °C, 2021
Day Maximum (09-21) 19.3 °C 13:38 13.1 °C 19.3 °C, 2018 10.8 °C, 2009
Max 10m Temp Rise 0.5 °C 10:47 0.5 °C 1.1 °C, 2012 0.3 °C, 2009
Max 1hr Temp Rise 2.5 °C 10:54 1.6 °C 4.9 °C, 2010 1.0 °C, 2009
Max 1hr Hum Rise 7% 12:47 6% 25%, 2012 1%, 2009
Max 10m Temp Fall 0.5 °C 16:12 0.4 °C 1.7 °C, 2012 0.3 °C, 2009
Max 1hr Temp Fall 1.0 °C 16:49 1.3 °C 4.5 °C, 2012 0.8 °C, 2009
Max 1hr Hum Fall 11% 10:15 8% 31%, 2012 1%, 2009
Max 10m Wind Speed 16.5 mph 12:37 10.2 mph 16.5 mph, 2018 5.3 mph, 2016
Minimum Feels-like 10.4 °C 06:22 4.4 °C 10.4 °C, 2018 -2.0 °C, 2016
Maximum Feels-like 20.2 °C 13:48 13.8 °C 20.2 °C, 2018 11.8 °C, 2016
Mean Feels-like 15.3 °C 9.4 °C 15.3 °C, 2018 5.9 °C, 2016
Air-frost Hrs 0 hrs 0 hrs 1 hrs, 2021 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 8.9 °C (+1.1) 5.9 °C (-1.5) 15.1 °C (+7.3), 2010 3.1 °C (-4.7), 2009
Humidity Range 28% 22% 60%, 2010 3%, 2009
Pressure Range 8 hPa 8 hPa 25 hPa, 2012 2 hPa, 2011
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 4 [32%]37 hrs (46%) [18%] 12.5 [99%], 2010 0 [0%], 2009
Wet Hours 055 hrs (209%) [13%] 8, 2009 0, 2010
Cloud Cover am: Mostly Cloudy transitioned to Partly Cloudy
pm: Partly Cloudy transitioned to Mostly Cloudy
Events None
Comments -
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
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

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Webcam Summary of Cloud Conditions

daycamsumLarge resolution version

Wind rose