Daily Report for 21st May 2017

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 9.6 °C (-0.0) 05:34 9.1 °C (+0.6) 13.5 °C (+3.9), 2016 5.5 °C (-4.1), 2015
Maximum Temperature 20.7 °C (+2.4) 17:32 16.9 °C (-0.4) 27.4 °C (+9.1), 2020 12.7 °C (-5.6), 2021
Mean Temperature 15.3 °C (+1.2) 12.8 °C (+0.1) 21.4 °C, 2020 11.3 °C, 2021
Minimum Humidity 42% 19:00 54% 84%, 2024 28%, 2020
Maximum Humidity 83% 06:08 83% 96%, 2024 81%, 2015
Mean Humidity 62% 70% 91%, 2024 55%, 2011
Minimum Pressure 1020 hPa 21:25 1012 hPa 1029 hPa, 2010 996 hPa, 2021
Maximum Pressure 1027 hPa 09:29 1020 hPa 1032 hPa, 2010 1002 hPa, 2021
Mean Pressure 1024 hPa 1016 hPa 1030 hPa, 2010 998 hPa, 2021
Mean Wind Speed 4.5 mph (-0.2) 4.4 mph (-0.3) 13.9 mph, 2021 2.2 mph, 2018
Maximum Wind Speed 10.6 mph 10:30 11.5 mph 23.5 mph, 2021 7.1 mph, 2024
Maximum Gust 15.7 mph 10:31 17.8 mph 42.2 mph, 2021 11.5 mph, 2024
Mean Wind Direction SSW
Rainfall 0.0 mm 65.8 mm (211%) 18.8 mm, 2024
Maximum Hourly Rain n/a 6.6, 2024
Maximum 10-min Rain n/a 2, 2024
Maximum Rain Rate n/a 60, 2024
Minimum Dew Point 5.8 °C 19:37 4.9 °C 9.5 °C, 2010 1.2 °C, 2015
Maximum Dew Point 9.6 °C 08:51 9.4 °C 15.5 °C, 2020 7.6 °C, 2015
Mean Dew Point 7.6 °C 7.2 °C 12.2 °C, 2010 3.8 °C, 2015
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 9.6 °C 05:34 9.4 °C 13.5 °C, 2016 5.5 °C, 2015
Day Maximum (09-21) 20.7 °C 17:32 16.9 °C 27.4 °C, 2020 12.7 °C, 2021
Max 10m Temp Rise 0.7 °C 09:51 0.6 °C 1.7 °C, 2010 0.3 °C, 2024
Max 1hr Temp Rise 2.6 °C 10:30 2.0 °C 5.7 °C, 2011 0.9 °C, 2024
Max 1hr Hum Rise 11% 22:44 9% 14%, 2018 3%, 2024
Max 10m Temp Fall 0.4 °C 22:12 0.5 °C 1.0 °C, 2010 0.2 °C, 2012
Max 1hr Temp Fall 1.7 °C 22:47 1.7 °C 2.4 °C, 2020 0.7 °C, 2012
Max 1hr Hum Fall 14% 10:01 10% 25%, 2010 2%, 2024
Max 10m Wind Speed 7.7 mph 15:38 8.7 mph 18.3 mph, 2021 5.2 mph, 2024
Minimum Feels-like 7.4 °C 05:29 7.7 °C 15.1 °C, 2020 3.0 °C, 2015
Maximum Feels-like 21.3 °C 16:11 17.7 °C 29.8 °C, 2020 13.1 °C, 2021
Mean Feels-like 15.5 °C 13.0 °C 23.3 °C, 2020 11.6 °C, 2021
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 11.1 °C (+2.4) 7.8 °C (-1.0) 14.6 °C (+5.9), 2015 2.8 °C (-5.9), 2021
Humidity Range 41% 29% 58%, 2020 12%, 2024
Pressure Range 7 hPa 8 hPa 10 hPa, 2014 2 hPa, 2012
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 10 [69%]83 hrs (66%) [28%] 13.5 [94%], 2011 0 [0%], 2021
Wet Hours 039 hrs (144%) [7.7%] 9, 2024 0, 2009
Cloud Cover am: Partly Cloudy
pm: Mostly Sunny
Events None
Comments -
Extra Comments
Issues None known
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 21st May 2017.
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

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Webcam Summary of Cloud Conditions

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Wind rose