Daily Report for 17th December 2017

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature -0.3 °C (-3.8) 03:39 2.2 °C (-1.5) 11.8 °C (+8.3), 2015 -6.0 °C (-9.5), 2010
Maximum Temperature 8.9 °C (+1.1) 21:47 6.6 °C (-1.8) 15.2 °C (+7.4), 2015 -0.8 °C (-8.6), 2010
Mean Temperature 4.3 °C (-1.3) 4.4 °C (-1.7) 13.6 °C, 2015 -3.0 °C, 2010
Minimum Humidity 83% 23:55 77% 92%, 2013 67%, 2015
Maximum Humidity 97% 13:00 92% 98%, 2009 84%, 2016
Mean Humidity 95% 86% 96%, 2013 79%, 2015
Minimum Pressure 1019 hPa 19:01 1007 hPa 1040 hPa, 2021 995 hPa, 2010
Maximum Pressure 1025 hPa 08:02 1018 hPa 1043 hPa, 2021 1002 hPa, 2010
Mean Pressure 1022 hPa 1012 hPa 1041 hPa, 2021 998 hPa, 2010
Mean Wind Speed 4.5 mph (-0.6) 5.4 mph (+0.3) 9.0 mph, 2009 0.7 mph, 2016
Maximum Wind Speed 11.5 mph 23:49 12.9 mph 22.8 mph, 2009 4.6 mph, 2016
Maximum Gust 20.7 mph 18:32 21.3 mph 33.1 mph, 2009 6.3 mph, 2016
Mean Wind Direction WSW
Rainfall 3.3 mm 57.6 mm (184%) 6.1 mm, 2013
Maximum Hourly Rain 1.1 mm 15:35 2.1 mm, 2014
Maximum 10-min Rain 0.4 mm 15:35 0.7 mm, 2013
Maximum Rain Rate 2.6 mm/h 15:30 3.6 mm/h, 2014
Minimum Dew Point -1.0 °C 03:39 -0.0 °C 8.3 °C, 2015 -8.0 °C, 2010
Maximum Dew Point 8.4 °C 21:10 4.7 °C 12.4 °C, 2015 -3.8 °C, 2010
Mean Dew Point 3.6 °C 2.3 °C 10.0 °C, 2015 -5.8 °C, 2010
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) -0.3 °C 03:39 2.8 °C 12.7 °C, 2015 -4.4 °C, 2022
Day Maximum (09-21) * 8.8 °C * 20:56 6.4 °C 15.2 °C, 2015 -0.8 °C, 2010
Max 10m Temp Rise 0.3 °C 11:12 0.3 °C 0.6 °C, 2016 0.2 °C, 2010
Max 1hr Temp Rise 1.3 °C 14:58 1.1 °C 2.3 °C, 2022 0.5 °C, 2019
Max 1hr Hum Rise 4% 13:19 5% 12%, 2009 1%, 2023
Max 10m Temp Fall 0.3 °C 23:38 0.4 °C 0.5 °C, 2010 0.1 °C, 2014
Max 1hr Temp Fall 1.1 °C 23:59 1.1 °C 1.6 °C, 2010 0.3 °C, 2014
Max 1hr Hum Fall 12% 23:39 6% 12%, 2017 2%, 2016
Max 10m Wind Speed 9.1 mph 18:36 10.0 mph 15.1 mph, 2009 3.5 mph, 2016
Minimum Feels-like -3.7 °C 01:51 -2.7 °C 13.0 °C, 2015 -9.0 °C, 2010
Maximum Feels-like 8.3 °C 21:45 5.8 °C 16.9 °C, 2015 -0.8 °C, 2010
Mean Feels-like 1.9 °C 1.6 °C 14.9 °C, 2015 -5.7 °C, 2010
Air-frost Hrs 2 hrs 1 hrs 24 hrs, 2010 0 hrs, 2011
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 9.2 °C (+4.9) 4.4 °C (-0.3) 9.2 °C (+4.9), 2017 1.6 °C (-2.7), 2019
Humidity Range 14% 15% 26%, 2009 4%, 2019
Pressure Range 6 hPa 12 hPa 11 hPa, 2018 2 hPa, 2021
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]35 hrs (97%) [29%] 6 [86%], 2012 0 [0%], 2016
Wet Hours 5
[Mean rain rate: 0.7 mm/h]
50 hrs (148%) [12%] 12, 2019 0, 2016
Cloud Cover Overcast
Events Air Frost
Comments pm Rain
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 17th December 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