Daily Report for 11th May 2015

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 13.5 °C (+5.2) 01:51 9.2 °C (+1.4) 14.7 °C (+6.3), 2016 3.1 °C (-5.2), 2010
Maximum Temperature 21.7 °C (+4.5) 16:20 17.0 °C (+0.3) 24.0 °C (+6.8), 2025 9.2 °C (-8.0), 2010
Mean Temperature 16.8 °C (+4.8) 12.9 °C (+0.8) 17.7 °C, 2025 6.8 °C, 2010
Minimum Humidity 45% 20:19 45% 80%, 2016 34%, 2025
Maximum Humidity 79% 08:01 87% 95%, 2024 72%, 2020
Mean Humidity 62% 67% 88%, 2016 54%, 2025
Minimum Pressure 1016 hPa 13:38 1005 hPa 1021 hPa, 2009 993 hPa, 2017
Maximum Pressure 1020 hPa 00:37 1013 hPa 1033 hPa, 2012 1001 hPa, 2017
Mean Pressure 1017 hPa 1009 hPa 1023 hPa, 2012 995 hPa, 2017
Mean Wind Speed 5.6 mph (+0.9) 7.3 mph (+2.6) 9.9 mph, 2014 2.0 mph, 2019
Maximum Wind Speed 14.0 mph 15:30 17.1 mph 18.5 mph, 2013 8.6 mph, 2016
Maximum Gust 20.0 mph 15:29 26.1 mph 30.0 mph, 2020 11.5 mph, 2016
Mean Wind Direction SW
Rainfall 0.0 mm 23.8 mm (146%) 17.7 mm, 2016
Maximum Hourly Rain n/a 8.1, 2016
Maximum 10-min Rain n/a 4.1, 2016
Maximum Rain Rate n/a 54, 2016
Minimum Dew Point 4.0 °C 23:31 2.8 °C 9.1 °C, 2022 -1.5 °C, 2020
Maximum Dew Point 11.7 °C 11:54 10.1 °C 18.8 °C, 2016 1.4 °C, 2010
Mean Dew Point 9.1 °C 6.5 °C 14.4 °C, 2016 -0.2 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 13.5 °C 01:51 9.3 °C 14.7 °C, 2016 3.1 °C, 2010
Day Maximum (09-21) 21.7 °C 16:20 17.0 °C 24.0 °C, 2025 9.2 °C, 2010
Max 10m Temp Rise 0.6 °C 10:51 0.6 °C 1.0 °C, 2011 0.4 °C, 2010
Max 1hr Temp Rise 2.3 °C 11:04 2.0 °C 4.4 °C, 2018 1.2 °C, 2016
Max 1hr Hum Rise 4% 22:15 8% 24%, 2013 3%, 2016
Max 10m Temp Fall 0.5 °C 18:30 0.5 °C 1.3 °C, 2013 0.3 °C, 2010
Max 1hr Temp Fall 1.6 °C 19:08 1.3 °C 4.0 °C, 2013 1.2 °C, 2010
Max 1hr Hum Fall 9% 11:06 13% 20%, 2018 9%, 2015
Max 10m Wind Speed 10.7 mph 00:10 13.2 mph 13.8 mph, 2020 5.5 mph, 2010
Minimum Feels-like 13.7 °C 23:59 6.9 °C 14.9 °C, 2016 -0.7 °C, 2020
Maximum Feels-like 23.5 °C 16:18 17.7 °C 26.0 °C, 2024 7.9 °C, 2010
Mean Feels-like 17.8 °C 13.0 °C 20.2 °C, 2016 4.9 °C, 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 8.2 °C (-0.7) 7.9 °C (-1.1) 15.1 °C (+6.2), 2025 4.4 °C (-4.5), 2022
Humidity Range 34% 41% 53%, 2012 14%, 2016
Pressure Range 4 hPa 8 hPa 20 hPa, 2019 2 hPa, 2021
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 6 [43%]45 hrs (69%) [30%] 13 [93%], 2025 0.5 [4%], 2016
Wet Hours 018 hrs (123%) [6.6%] 8, 2016 0, 2009
Cloud Cover am: Mostly Cloudy transitioned to Hazy
pm: Partly Cloudy
Events None
Comments -
Extra Comments
Issues Wind sensor restored - batteries replaced - at 1830
Observer Absent? Yes - observations may be unreliable
Pond Temperature @ Hampstead Heath 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 11th May 2015.
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

day graph

Webcam Summary of Cloud Conditions

daycamsumLarge resolution version

Wind rose