Daily Report for 21st January 2018

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 0.7 °C (-2.2) 04:52 3.4 °C (+0.4) 7.1 °C (+4.2), 2012 -2.6 °C (-5.5), 2019
Maximum Temperature 9.8 °C (+2.0) 23:55 8.0 °C (+0.2) 12.7 °C (+4.9), 2024 1.4 °C (-6.4), 2013
Mean Temperature 3.3 °C (-0.1) 5.6 °C (+0.3) 10.0 °C, 2012 -0.0 °C, 2013
Minimum Humidity 91% 09:39 75% 91%, 2018 47%, 2017
Maximum Humidity 98% 21:00 93% 98%, 2013 80%, 2017
Mean Humidity 95% 85% 95%, 2018 66%, 2017
Minimum Pressure 1006 hPa 21:30 1002 hPa 1040 hPa, 2020 976 hPa, 2021
Maximum Pressure 1016 hPa 09:01 1013 hPa 1045 hPa, 2020 988 hPa, 2021
Mean Pressure 1011 hPa 1008 hPa 1042 hPa, 2020 986 hPa, 2021
Mean Wind Speed 3.4 mph (-1.8) 6.5 mph (+1.3) 13.4 mph, 2024 1.5 mph, 2017
Maximum Wind Speed 10.6 mph 11:25 17.2 mph 31.7 mph, 2024 5.8 mph, 2020
Maximum Gust 16.1 mph 11:32 27.6 mph 47.2 mph, 2024 8.1 mph, 2013
Mean Wind Direction SSW
Rainfall / Snow-melt approx. 12.3 mm 56.1 mm (140%) 12.3 mm, 2018
Maximum Hourly Rain 3.1 mm 17:35 3.1 mm, 2018
Maximum 10-min Rain 0.7 mm 17:22 0.7 mm, 2018
Maximum Rain Rate 4.4 mm/h 13:05 4.4 mm/h, 2018
Minimum Dew Point -0.3 °C 04:40 1.0 °C 1.3 °C, 2021 -8.5 °C, 2017
Maximum Dew Point 9.3 °C 22:34 5.8 °C 10.3 °C, 2024 -1.9 °C, 2017
Mean Dew Point 2.5 °C 3.1 °C 6.9 °C, 2024 -5.1 °C, 2017
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 0.7 °C 04:52 4.0 °C 8.5 °C, 2012 -2.6 °C, 2019
Day Maximum (09-21) * 7.7 °C * 20:58 7.6 °C 12.4 °C, 2024 1.4 °C, 2013
Max 10m Temp Rise 0.4 °C 20:02 0.4 °C 0.8 °C, 2016 0.2 °C, 2011
Max 1hr Temp Rise 1.4 °C 20:17 1.0 °C 2.4 °C, 2020 0.4 °C, 2015
Max 1hr Hum Rise 2% 03:34 5% 13%, 2024 2%, 2014
Max 10m Temp Fall 0.3 °C 11:59 0.4 °C 0.7 °C, 2023 0.2 °C, 2010
Max 1hr Temp Fall 0.9 °C 12:50 1.0 °C 2.9 °C, 2023 0.5 °C, 2019
Max 1hr Hum Fall 3% 09:40 7% 22%, 2017 2%, 2015
Max 10m Wind Speed 8.4 mph 11:31 13.2 mph 25.0 mph, 2024 4.4 mph, 2020
Minimum Feels-like -3.7 °C 13:36 -1.0 °C 4.4 °C, 2012 -5.1 °C, 2022
Maximum Feels-like 9.2 °C 23:34 7.3 °C 14.0 °C, 2024 1.3 °C, 2013
Mean Feels-like 1.3 °C 2.8 °C 9.3 °C, 2012 -1.1 °C, 2013
Air-frost Hrs 0 hrs 0 hrs 13 hrs, 2013 0 hrs, 2010
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 9.1 °C (+4.3) 4.5 °C (-0.2) 9.1 °C (+4.3), 2018 2.8 °C (-2.0), 2015
Humidity Range 7% 17% 44%, 2009 7%, 2018
Pressure Range 10 hPa 11 hPa 18 hPa, 2024 2 hPa, 2011
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]36 hrs (78%) [23%] 7.7 [101%], 2017 0 [0%], 2015
Wet Hours 10
[Mean rain rate: 1.2 mm/h]		47 hrs (104%) [9.3%] 10, 2018 , 2009
Cloud Cover Overcast
Events Snowfall: ~0.3 cm
Comments brief 0830 Snow then all dayRain
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 January 2018.
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