Daily Report for 20th July 2017

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 15.3 °C (+0.7) 23:57 15.9 °C (+1.9) 18.7 °C (+4.1), 2014 11.2 °C (-3.4), 2020
Maximum Temperature 20.4 °C (-2.9) 17:13 24.7 °C (+1.8) 31.7 °C (+8.4), 2021 18.6 °C (-4.7), 2012
Mean Temperature 18.2 °C (-1.1) 20.2 °C (+1.8) 24.3 °C, 2016 14.9 °C, 2012
Minimum Humidity 41% 17:41 45% 73%, 2024 31%, 2016
Maximum Humidity 85% 06:23 78% 95%, 2019 56%, 2010
Mean Humidity 68% 61% 81%, 2024 43%, 2010
Minimum Pressure 1006 hPa 06:07 1013 hPa 1022 hPa, 2020 1006 hPa, 2017
Maximum Pressure 1011 hPa 18:42 1020 hPa 1026 hPa, 2020 1010 hPa, 2011
Mean Pressure 1009 hPa 1017 hPa 1024 hPa, 2020 1009 hPa, 2017
Mean Wind Speed 5.7 mph (+1.4) 3.6 mph (-0.7) 8.3 mph, 2016 1.9 mph, 2021
Maximum Wind Speed 14.4 mph 11:54 11.2 mph 20.8 mph, 2016 7.8 mph, 2014
Maximum Gust 24.1 mph 13:06 17.1 mph 30.6 mph, 2016 10.7 mph, 2011
Mean Wind Direction WSW
Rainfall 0.5 mm 45.9 mm (155%) 9.2 mm, 2019
Maximum Hourly Rain 0.3 mm 03:03 4.8 mm, 2021
Maximum 10-min Rain 0.3 mm 03:03 3.0 mm, 2011
Maximum Rain Rate n/a 20, 2011
Minimum Dew Point 6.1 °C 19:15 9.1 °C 15.6 °C, 2024 1.0 °C, 2015
Maximum Dew Point 16.3 °C 09:17 14.7 °C 20.5 °C, 2021 10.2 °C, 2020
Mean Dew Point 11.9 °C 12.0 °C 17.8 °C, 2021 8.6 °C, 2020
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 17.7 °C * 05:23 16.0 °C 20.9 °C, 2016 11.2 °C, 2020
Day Maximum (09-21) 20.4 °C 17:13 24.7 °C 31.7 °C, 2021 18.6 °C, 2012
Max 10m Temp Rise 0.7 °C 14:00 0.6 °C 0.9 °C, 2013 0.4 °C, 2009
Max 1hr Temp Rise 2.4 °C 14:41 2.2 °C 3.0 °C, 2016 1.3 °C, 2011
Max 1hr Hum Rise 10% 21:06 8% 23%, 2021 6%, 2009
Max 10m Temp Fall 0.6 °C 11:12 0.5 °C 1.2 °C, 2021 0.3 °C, 2013
Max 1hr Temp Fall 2.3 °C 11:26 1.9 °C 4.8 °C, 2021 1.1 °C, 2013
Max 1hr Hum Fall 17% 14:58 10% 17%, 2017 7%, 2010
Max 10m Wind Speed 10.7 mph 16:43 8.2 mph 16.7 mph, 2016 3.7 mph, 2009
Minimum Feels-like 15.7 °C 23:55 17.5 °C 23.5 °C, 2014 11.6 °C, 2020
Maximum Feels-like 24.5 °C 09:29 27.5 °C 38.6 °C, 2021 20.5 °C, 2011
Mean Feels-like 20.6 °C 22.6 °C 29.3 °C, 2021 16.7 °C, 2012
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 5.1 °C (-3.6) 8.9 °C (-0.1) 14.4 °C (+5.7), 2021 5.1 °C (-3.6), 2017
Humidity Range 44% 34% 53%, 2021 17%, 2024
Pressure Range 5 hPa 6 hPa 11 hPa, 2010 2 hPa, 2011
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 3.4 [23%]127 hrs (99%) [43%] 14 [96%], 2020 0 [0%], 2015
Wet Hours 1
[Mean rain rate: 0.5 mm/h]
17 hrs (78%) [3.5%] 4, 2011 0, 2009
Cloud Cover am: Mostly Cloudy
pm: Partly Cloudy transitioned to Mostly Cloudy
Events None
Comments Showers
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 20th July 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

daycamsumLarge resolution version

Wind rose