Daily Report for 30th April 2018

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 4.7 °C (-2.2) 04:35 8.1 °C (+2.1) 10.9 °C (+4.0), 2011 1.8 °C (-5.1), 2021
Maximum Temperature 8.7 °C (-7.3) 17:18 15.1 °C (+0.6) 20.4 °C (+4.4), 2014 8.7 °C (-7.3), 2018
Mean Temperature 6.4 °C (-4.8) 11.5 °C (+1.4) 15.1 °C, 2011 6.4 °C, 2018
Minimum Humidity 62% 19:15 62% 62%, 2018 36%, 2013
Maximum Humidity 90% 10:35 89% 97%, 2014 71%, 2017
Mean Humidity 78% 78% 83%, 2020 52%, 2017
Minimum Pressure 1004 hPa 10:07 1008 hPa 1027 hPa, 2022 993 hPa, 2020
Maximum Pressure 1010 hPa 23:53 1015 hPa 1033 hPa, 2022 998 hPa, 2020
Mean Pressure 1007 hPa 1011 hPa 1030 hPa, 2022 996 hPa, 2020
Mean Wind Speed 7.9 mph (+3.0) 5.4 mph (+0.5) 7.9 mph, 2018 0.9 mph, 2022
Maximum Wind Speed 17.2 mph 04:13 14.0 mph 18.1 mph, 2011 7.0 mph, 2022
Maximum Gust 28.8 mph 03:14 21.8 mph 30.0 mph, 2020 11.5 mph, 2019
Mean Wind Direction N
Rainfall 5.3 mm 58.5 mm (139%) 10.9 mm, 2020
Maximum Hourly Rain 0.9 mm 10:00 4.6 mm, 2020
Maximum 10-min Rain 0.2 mm 04:24 1.5 mm, 2020
Maximum Rain Rate 1.1 mm/h 03:12 30 mm/h, 2010
Minimum Dew Point 1.0 °C 21:16 4.8 °C 5.9 °C, 2010 -3.1 °C, 2016
Maximum Dew Point 3.8 °C 10:35 9.4 °C 12.5 °C, 2014 2.9 °C, 2013
Mean Dew Point 2.8 °C 7.3 °C 8.7 °C, 2024 -0.9 °C, 2016
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 4.7 °C 05:19 8.3 °C 10.9 °C, 2011 1.8 °C, 2021
Day Maximum (09-21) 8.7 °C 17:18 15.0 °C 20.4 °C, 2014 8.7 °C, 2018
Max 10m Temp Rise 0.4 °C 11:29 0.5 °C 0.9 °C, 2021 0.4 °C, 2011
Max 1hr Temp Rise 0.9 °C 12:07 1.7 °C 4.0 °C, 2024 0.9 °C, 2018
Max 1hr Hum Rise 6% 02:04 8% 21%, 2021 5%, 2009
Max 10m Temp Fall 0.3 °C 01:37 0.5 °C 1.2 °C, 2020 0.3 °C, 2018
Max 1hr Temp Fall 0.9 °C 22:45 1.5 °C 4.1 °C, 2020 0.9 °C, 2018
Max 1hr Hum Fall 9% 12:19 9% 20%, 2014 6%, 2017
Max 10m Wind Speed 13.0 mph 07:01 10.5 mph 14.1 mph, 2020 5.2 mph, 2022
Minimum Feels-like -1.2 °C 04:08 5.7 °C 11.3 °C, 2011 -1.2 °C, 2018
Maximum Feels-like 8.0 °C 17:55 15.8 °C 20.9 °C, 2024 8.0 °C, 2018
Mean Feels-like 2.8 °C 11.1 °C 15.4 °C, 2011 2.8 °C, 2018
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 4.0 °C (-5.1) 7.0 °C (-1.4) 14.5 °C (+5.4), 2022 4.0 °C (-5.1), 2018
Humidity Range 28% 27% 60%, 2014 24%, 2009
Pressure Range 6 hPa 7 hPa 13 hPa, 2016 2 hPa, 2021
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 0 [0%]112 hrs (69%) [30%] 13.4 [100%], 2011 0 [0%], 2018
Wet Hours 12
[Mean rain rate: 0.4 mm/h]
87 hrs (189%) [12%] 12, 2018 0, 2011
Cloud Cover Overcast
Events None
Comments 01-15 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 30th April 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.
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Daily Graph of Conditions

day graph

Webcam Summary of Cloud Conditions

daycamsumLarge resolution version

Wind rose