Daily Report for 31st May 2009

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 10.2 °C (-0.6) 05:45 8.9 °C (-0.2) 14.8 °C (+4.0), 2018 6.8 °C (-4.0), 2014
Maximum Temperature 25.3 °C (+6.0) 16:12 18.7 °C (+0.8) 25.3 °C (+6.0), 2009 13.2 °C (-6.1), 2016
Mean Temperature 17.4 °C (+2.7) 13.5 °C (+0.3) 18.1 °C, 2017 11.9 °C, 2022
Minimum Humidity 36% 16:25 46% 78%, 2024 35%, 2011
Maximum Humidity 85% 07:27 87% 97%, 2018 78%, 2020
Mean Humidity 64% 68% 88%, 2018 55%, 2020
Minimum Pressure 1024 hPa 17:41 1015 hPa 1026 hPa, 2023 1004 hPa, 2015
Maximum Pressure 1026 hPa 17:35 1021 hPa 1030 hPa, 2023 1012 hPa, 2015
Mean Pressure 1025 hPa 1018 hPa 1028 hPa, 2023 1007 hPa, 2015
Mean Wind Speed 4.9 mph (+0.2) 5.8 mph (+1.1) 7.2 mph, 2016 1.0 mph, 2014
Maximum Wind Speed n/a 0.0 mph 17, 2015 6.4, 2014
Maximum Gust 22.0 mph 23.9 mph 26.5 mph, 2020 8.7 mph, 2014
Mean Wind Direction n/a
Rainfall 0.0 mm 26.3 mm (57%) 12.4 mm, 2016
Maximum Hourly Rain n/a 5.8, 2016
Maximum 10-min Rain n/a 1.3, 2016
Maximum Rain Rate n/a 24, 2016
Minimum Dew Point 7.1 °C 01:31 4.1 °C 14.2 °C, 2018 0.2 °C, 2015
Maximum Dew Point 13.3 °C 13:42 10.4 °C 18.2 °C, 2018 8.8 °C, 2011
Mean Dew Point 9.9 °C 7.2 °C 15.9 °C, 2018 5.1 °C, 2011
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 10.2 °C 9.1 °C 14.8 °C, 2018 6.8 °C, 2014
Day Maximum (09-21) 25.3 °C 18.7 °C 25.3 °C, 2009 12.9 °C, 2016
Max 10m Temp Rise n/a 14:36 0.7 °C 1, 2021 0.3, 2016
Max 1hr Temp Rise n/a 15:27 2.2 °C 4.4, 2021 0.8, 2016
Max 1hr Hum Rise n/a 14:26 8% 17, 2022 4, 2018
Max 10m Temp Fall n/a 14:26 0.5 °C 1.6, 2022 0.2, 2016
Max 1hr Temp Fall n/a 14:26 1.5 °C 3.1, 2022 0.6, 2016
Max 1hr Hum Fall n/a 15:27 13% 18, 2014 2, 2016
Max 10m Wind Speed n/a 0.0 mph 12.8, 2015 3.9, 2014
Minimum Feels-like n/a 0.0 °C 18.3, 2018 5.6, 2011
Maximum Feels-like n/a 0.0 °C 28.6, 2018 14.7, 2016
Mean Feels-like n/a 0.0 °C 22.7, 2018 12.4, 2011
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 15.1 °C (+6.6) 9.8 °C (+1.0) 15.3 °C (+6.8), 2021 2.3 °C (-6.2), 2016
Humidity Range 49% 41% 52%, 2011 13%, 2024
Pressure Range 2 hPa 5 hPa 15 hPa, 2011 2 hPa, 2009
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 11.6 [79%]194 hrs (103%) [44%] 14.8 [100%], 2020 0 [0%], 2016
Wet Hours 028 hrs (69%) [3.7%] 7, 2015 0, 2009
Cloud Cover not available
Events None
Comments
Extra Comments
Issues Tmax corrected as unreliable
Observer Absent? No
Pond Temperature (Heath) 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 31st 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