Daily Report for 30th July 2017

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 14.8 °C (+0.1) 06:53 15.2 °C (+1.0) 17.7 °C (+3.0), 2018 9.1 °C (-5.6), 2011
Maximum Temperature 20.2 °C (-3.1) 15:00 23.4 °C (+0.3) 31.0 °C (+7.7), 2024 17.8 °C (-5.5), 2021
Mean Temperature 17.6 °C (-1.5) 19.1 °C (+0.7) 23.4 °C, 2024 15.2 °C, 2015
Minimum Humidity 51% 18:18 48% 74%, 2021 31%, 2020
Maximum Humidity 86% 03:06 80% 95%, 2009 73%, 2014
Mean Humidity 70% 65% 85%, 2013 54%, 2020
Minimum Pressure 1004 hPa 04:35 1011 hPa 1019 hPa, 2025 999 hPa, 2021
Maximum Pressure 1009 hPa 23:46 1017 hPa 1025 hPa, 2011 1008 hPa, 2019
Mean Pressure 1007 hPa 1015 hPa 1022 hPa, 2011 1004 hPa, 2021
Mean Wind Speed 5.7 mph (+1.4) 4.0 mph (-0.3) 7.6 mph, 2019 1.0 mph, 2024
Maximum Wind Speed 14.0 mph 17:28 11.9 mph 19.9 mph, 2019 7.2 mph, 2024
Maximum Gust 21.0 mph 15:33 18.1 mph 36.9 mph, 2019 10.4 mph, 2024
Mean Wind Direction WSW
Rainfall 17.8 mm 89.0 mm (200%) 17.8 mm, 2017
Maximum Hourly Rain 16.0 mm 02:51 16.0 mm, 2017
Maximum 10-min Rain 5.1 mm 02:36 5.1 mm, 2017
Maximum Rain Rate 50 mm/h 02:32 50 mm/h, 2017
Minimum Dew Point 9.0 °C 19:32 9.4 °C 13.8 °C, 2024 2.5 °C, 2012
Maximum Dew Point 15.0 °C 01:52 14.5 °C 19.1 °C, 2024 8.9 °C, 2015
Mean Dew Point 11.8 °C 11.9 °C 16.4 °C, 2024 6.2 °C, 2012
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 14.8 °C 06:53 15.3 °C 18.2 °C, 2019 9.1 °C, 2011
Day Maximum (09-21) 20.2 °C 15:00 23.4 °C 31.0 °C, 2024 17.8 °C, 2021
Max 10m Temp Rise 0.5 °C 12:55 0.6 °C 1.0 °C, 2011 0.4 °C, 2016
Max 1hr Temp Rise 1.7 °C 09:24 2.1 °C 4.5 °C, 2011 1.4 °C, 2013
Max 1hr Hum Rise 6% 23:51 8% 19%, 2020 5%, 2013
Max 10m Temp Fall 0.4 °C 19:16 0.5 °C 0.8 °C, 2021 0.3 °C, 2010
Max 1hr Temp Fall 1.4 °C 19:54 1.9 °C 3.0 °C, 2020 1.2 °C, 2010
Max 1hr Hum Fall 12% 10:55 10% 17%, 2018 8%, 2013
Max 10m Wind Speed 11.4 mph 17:25 8.8 mph 15.9 mph, 2021 4.1 mph, 2024
Minimum Feels-like 17.1 °C 06:53 16.8 °C 20.7 °C, 2018 8.2 °C, 2011
Maximum Feels-like 22.2 °C 14:50 26.1 °C 37.5 °C, 2024 18.8 °C, 2015
Mean Feels-like 19.9 °C 21.4 °C 28.3 °C, 2024 15.4 °C, 2015
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 5.4 °C (-3.2) 8.2 °C (-0.6) 16.6 °C (+8.0), 2020 3.1 °C (-5.5), 2021
Humidity Range 35% 32% 56%, 2020 17%, 2021
Pressure Range 5 hPa 6 hPa 12 hPa, 2009 2 hPa, 2012
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 5.5 [39%]157 hrs (83%) [36%] 14.2 [100%], 2020 0.4 [3%], 2016
Wet Hours 2
[Mean rain rate: 9 mm/h]		45 hrs (135%) [6.2%] 8, 2019 0, 2011
Cloud Cover Partly Cloudy with periods of Mostly Cloudy
Events None
Comments o.night Rain/Showers
Extra Comments
Issues Rn data from N16
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 30th 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.
View monthly summary

Daily Graph of Conditions

day graph

Webcam Summary of Cloud Conditions

daycamsumLarge resolution version

Wind rose