Daily Report for 27th May 2009

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 8.5 °C (-1.9) 04:29 8.6 °C (-0.3) 15.1 °C (+4.7), 2017 7.5 °C (-2.9), 2015
Maximum Temperature 15.1 °C (-3.8) 19:50 17.9 °C (+0.3) 27.1 °C (+8.2), 2018 13.2 °C (-5.8), 2014
Mean Temperature 11.5 °C (-2.9) 13.0 °C (-0.0) 20.7 °C, 2018 11.5 °C, 2009
Minimum Humidity 69% 00:09 47% 89%, 2014 29%, 2012
Maximum Humidity 91% 23:45 86% 97%, 2014 65%, 2013
Mean Humidity 84% 68% 94%, 2014 47%, 2013
Minimum Pressure 1019 hPa 17:06 1014 hPa 1035 hPa, 2020 1004 hPa, 2013
Maximum Pressure 1024 hPa 23:25 1019 hPa 1037 hPa, 2020 1011 hPa, 2010
Mean Pressure 1022 hPa 1017 hPa 1036 hPa, 2020 1009 hPa, 2013
Mean Wind Speed 3.0 mph (-1.7) 6.0 mph (+1.3) 6.7 mph, 2013 1.6 mph, 2021
Maximum Wind Speed n/a 0.0 mph 19.2, 2013 7.9, 2021
Maximum Gust 13.0 mph 24.1 mph 28.5 mph, 2022 11.4 mph, 2021
Mean Wind Direction n/a
Rainfall 1.9 mm 26.3 mm (66%) 6.5 mm, 2014
Maximum Hourly Rain 0.8 mm 13:15 2.4 mm, 2018
Maximum 10-min Rain 0.3 mm 11:07 1.8 mm, 2018
Maximum Rain Rate 0.6 mm/h 12:45 40 mm/h, 2018
Minimum Dew Point 4.8 °C 01:12 3.8 °C 12.8 °C, 2018 0.4 °C, 2013
Maximum Dew Point 13.1 °C 18:38 9.9 °C 19.4 °C, 2018 5.3 °C, 2013
Mean Dew Point 8.8 °C 6.8 °C 16.1 °C, 2018 2.3 °C, 2013
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 8.5 °C 8.8 °C 15.1 °C, 2017 7.5 °C, 2015
Day Maximum (09-21) 15.1 °C 17.9 °C 27.1 °C, 2018 13.2 °C, 2014
Max 10m Temp Rise 0.4 °C 07:13 0.7 °C 0.9 °C, 2019 0.2 °C, 2014
Max 1hr Temp Rise 1.2 °C 16:45 2.2 °C 3.3 °C, 2018 0.6 °C, 2014
Max 1hr Hum Rise 5% 13:30 8% 15%, 2018 2%, 2014
Max 10m Temp Fall 0.2 °C 00:16 0.5 °C 1.1 °C, 2017 0.2 °C, 2009
Max 1hr Temp Fall 0.8 °C 01:03 1.5 °C 2.7 °C, 2017 0.8 °C, 2009
Max 1hr Hum Fall 4% 19:37 13% 15%, 2010 4%, 2009
Max 10m Wind Speed n/a 0.0 mph 13.5, 2017 5.2, 2021
Minimum Feels-like n/a 0.0 °C 16.9, 2017 5.3, 2013
Maximum Feels-like n/a 0.0 °C 33.7, 2018 15.4, 2014
Mean Feels-like n/a 0.0 °C 25.4, 2018 12.3, 2010
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 6.6 °C (-1.9) 9.3 °C (+0.6) 13.2 °C (+4.7), 2012 3.5 °C (-5.0), 2014
Humidity Range 22% 39% 46%, 2010 8%, 2014
Pressure Range 5 hPa 5 hPa 12 hPa, 2015 2 hPa, 2010
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]154 hrs (94%) [40%] 14.7 [101%], 2012 0 [0%], 2009
Wet Hours 5
[Mean rain rate: 0.4 mm/h]
28 hrs (79%) [4.3%] 10, 2014 0, 2011
Cloud Cover not available
Events None
Comments 0830-1330 SLight/Light Rain
Extra Comments
Issues None known
Observer Absent? No
Pond Temperature (Heath) 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 27th May 2009.
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 derived based on analysis of webcam observations, but may use data from our closest site, Heathrow, when needed.
Wet hrs are dervied algorithmically from rainfall data, though may be adjusted manually.
Rainfall totals may be manually adjusted after the fact to correct delayed or erroneous data.
Cloud cover and Events are manually reported, often with multi-week delays.
Data is generally reliable and accurate but should always be viewed with some quantity of salt to hand.
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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