Daily Report for 18th May 2009

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 9.2 °C (-0.0) 06:09 8.2 °C (-0.0) 12.7 °C (+3.5), 2022 3.9 °C (-5.3), 2018
Maximum Temperature 15.9 °C (-2.1) 12:53 17.0 °C (-0.2) 24.5 °C (+6.5), 2014 14.6 °C (-3.4), 2016
Mean Temperature 12.3 °C (-1.0) 12.3 °C (-0.1) 18.7 °C, 2014 11.7 °C, 2013
Minimum Humidity 53% 16:55 48% 71%, 2016 32%, 2020
Maximum Humidity 89% 05:05 85% 95%, 2019 75%, 2013
Mean Humidity 73% 69% 83%, 2024 56%, 2020
Minimum Pressure 1009 hPa 02:58 1014 hPa 1028 hPa, 2023 1002 hPa, 2012
Maximum Pressure 1018 hPa 23:33 1019 hPa 1030 hPa, 2023 1009 hPa, 2012
Mean Pressure 1014 hPa 1016 hPa 1029 hPa, 2023 1005 hPa, 2016
Mean Wind Speed 7.3 mph (+2.6) 6.6 mph (+1.9) 8.3 mph, 2015 0.4 mph, 2019
Maximum Wind Speed n/a 0.0 mph 21, 2015 5.8, 2019
Maximum Gust 30.0 mph 25.5 mph 39.8 mph, 2015 9.2 mph, 2019
Mean Wind Direction n/a
Rainfall trace 11.9 mm (45%) 15, 2017
Maximum Hourly Rain n/a 3.2, 2016
Maximum 10-min Rain n/a 2, 2016
Maximum Rain Rate n/a 30, 2016
Minimum Dew Point 5.3 °C 18:24 3.4 °C 8.3 °C, 2011 0.2 °C, 2015
Maximum Dew Point 8.9 °C 05:38 9.1 °C 15.6 °C, 2024 6.4 °C, 2013
Mean Dew Point 7.3 °C 6.4 °C 12.3 °C, 2024 4.9 °C, 2018
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 9.2 °C 8.5 °C 13.1 °C, 2011 3.9 °C, 2018
Day Maximum (09-21) 15.9 °C 17.0 °C 24.5 °C, 2014 14.6 °C, 2016
Max 10m Temp Rise 0.7 °C 15:39 0.7 °C 0.8 °C, 2012 0.4 °C, 2011
Max 1hr Temp Rise 2.2 °C 12:45 2.3 °C 4.0 °C, 2014 1.2 °C, 2011
Max 1hr Hum Rise 6% 22:05 9% 23%, 2021 5%, 2013
Max 10m Temp Fall 0.5 °C 04:28 0.5 °C 1.5 °C, 2021 0.3 °C, 2013
Max 1hr Temp Fall 1.2 °C 21:24 1.5 °C 3.5 °C, 2021 0.9 °C, 2012
Max 1hr Hum Fall 12% 12:56 14% 22%, 2015 7%, 2016
Max 10m Wind Speed n/a 0.0 mph 18, 2015 3.4, 2019
Minimum Feels-like n/a 0.0 °C 14.2, 2022 2.6, 2018
Maximum Feels-like n/a 0.0 °C 25.5, 2022 15.2, 2013
Mean Feels-like n/a 0.0 °C 20.1, 2022 11.4, 2013
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 6.7 °C (-2.0) 8.7 °C (-0.1) 14.2 °C (+5.5), 2018 3.4 °C (-5.3), 2016
Humidity Range 36% 37% 58%, 2014 15%, 2016
Pressure Range 9 hPa 5 hPa 15 hPa, 2015 2 hPa, 2020
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 5.8 [41%]94 hrs (88%) [38%] 13.5 [95%], 2014 0.1 [1%], 2016
Wet Hours 0.312 hrs (53%) [2.8%] 9, 2017 0, 2010
Cloud Cover not available
Events None
Comments occasional. Brief am SL. Showers
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 18th 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