Daily Report for 15th April 2009

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 8.3 °C (+2.4) 06:32 7.2 °C (+1.5) 10.8 °C (+4.9), 2013 0.9 °C (-5.0), 2021
Maximum Temperature 20.5 °C (+6.3) 14:52 15.6 °C (+1.8) 24.2 °C (+10.0), 2015 9.5 °C (-4.7), 2012
Mean Temperature 13.5 °C (+4.3) 10.8 °C (+1.7) 17.3 °C, 2015 5.7 °C, 2021
Minimum Humidity 60% 16:31 59% 67%, 2016 27%, 2015
Maximum Humidity 96% 08:44 92% 96%, 2009 70%, 2015
Mean Humidity 81% 78% 86%, 2016 48%, 2015
Minimum Pressure 1003 hPa 17:25 1009 hPa 1033 hPa, 2021 996 hPa, 2016
Maximum Pressure 1009 hPa 00:05 1015 hPa 1035 hPa, 2021 1005 hPa, 2016
Mean Pressure 1006 hPa 1012 hPa 1034 hPa, 2021 1000 hPa, 2016
Mean Wind Speed 3.2 mph (-1.7) 4.2 mph (-0.7) 10.7 mph, 2024 1.0 mph, 2016
Maximum Wind Speed n/a 0.0 mph 29.8, 2024 8.1, 2011
Maximum Gust 20.0 mph 19.3 mph 46.1 mph, 2024 10.7 mph, 2011
Mean Wind Direction n/a
Rainfall 2.5 mm 13.2 mm (63%) 21.1 mm, 2016
Maximum Hourly Rain 1.1 mm 05:34 6.9 mm, 2016
Maximum 10-min Rain 0.8 mm 05:22 2.1 mm, 2016
Maximum Rain Rate 33 mm/h 05:19 54 mm/h, 2024
Minimum Dew Point 7.4 °C 05:36 3.7 °C 7.4 °C, 2009 -4.6 °C, 2012
Maximum Dew Point 14.5 °C 13:22 9.5 °C 14.5 °C, 2009 2.4 °C, 2012
Mean Dew Point 10.0 °C 6.7 °C 10.0 °C, 2009 -0.9 °C, 2012
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) 8.3 °C 7.4 °C 11.0 °C, 2013 0.9 °C, 2021
Day Maximum (09-21) 20.5 °C 15.6 °C 24.2 °C, 2015 9.5 °C, 2012
Max 10m Temp Rise 1.0 °C 09:48 0.3 °C 1.1 °C, 2020 0.4 °C, 2011
Max 1hr Temp Rise 2.9 °C 10:43 0.9 °C 4.6 °C, 2020 1.5 °C, 2017
Max 1hr Hum Rise 4% 01:01 2% 26%, 2012 3%, 2017
Max 10m Temp Fall 0.4 °C 09:44 0.2 °C 3.9 °C, 2024 0.3 °C, 2013
Max 1hr Temp Fall 1.6 °C 19:11 0.5 °C 4.2 °C, 2024 1.1 °C, 2013
Max 1hr Hum Fall 14% 13:54 3% 21%, 2012 6%, 2016
Max 10m Wind Speed n/a 0.0 mph 19.9, 2024 5.4, 2011
Minimum Feels-like n/a 0.0 °C 10.8, 2013 -1.7, 2012
Maximum Feels-like n/a 0.0 °C 24.2, 2015 7.8, 2012
Mean Feels-like n/a 0.0 °C 17.3, 2015 3.1, 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 12.2 °C (+3.9) 8.4 °C (+0.3) 16.0 °C (+7.7), 2020 3.9 °C (-4.4), 2016
Humidity Range 36% 33% 52%, 2020 24%, 2016
Pressure Range 6 hPa 6 hPa 18 hPa, 2023 3 hPa, 2021
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 6.3 [51%]73 hrs (94%) [40%] 12.6 [101%], 2020 0.1 [1%], 2011
Wet Hours 3
[Mean rain rate: 0.8 mm/h]
20 hrs (87%) [5.6%] 16, 2016 0, 2010
Cloud Cover not available
Events None
Comments M. 00-30 Rain, H. 03-06, 11 L. Showerower
Extra Comments
Issues None known
Observer Absent? No
Pond Temperature (Heath) 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 15th April 2009.
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

daygraph daygraph 2 daygraph-wdir

Webcam Summary of Cloud Conditions


Webcam summary not available for this day

Wind rose