Daily Report for 11th September 2012

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Measure Value (anomaly) Time Month cumul. Record High Record Low
Minimum Temperature 11.4 °C (-0.5) 23:59 12.0 °C (-0.3) 19.3 °C (+7.4), 2023 8.1 °C (-3.8), 2020
Maximum Temperature 17.4 °C (-2.2) 15:39 22.6 °C (+2.2) 25.1 °C (+5.5), 2023 16.3 °C (-3.3), 2013
Mean Temperature 15.6 °C (-1.4) 17.2 °C (+1.0) 21.7 °C, 2023 13.6 °C, 2013
Minimum Humidity 37% 17:56 43% 76%, 2018 37%, 2012
Maximum Humidity 79% 03:54 85% 97%, 2022 79%, 2012
Mean Humidity 58% 65% 84%, 2022 58%, 2012
Minimum Pressure 1009 hPa 06:03 1019 hPa 1034 hPa, 2009 991 hPa, 2017
Maximum Pressure 1017 hPa 23:30 1024 hPa 1038 hPa, 2009 1001 hPa, 2017
Mean Pressure 1012 hPa 1021 hPa 1036 hPa, 2009 994 hPa, 2017
Mean Wind Speed 7.0 mph (+3.1) 4.2 mph (+0.3) 8.3 mph, 2017 2.1 mph, 2020
Maximum Wind Speed 12.5 mph 09:58 10.3 mph 21.5 mph, 2011 7.4 mph, 2014
Maximum Gust 20.4 mph 11:01 15.3 mph 31.7 mph, 2011 9.8 mph, 2014
Mean Wind Direction W
Rainfall 0.0 mm 0.0 mm (0%) 7.7 mm, 2017
Maximum Hourly Rain n/a 5.5, 2017
Maximum 10-min Rain n/a 3.5, 2017
Maximum Rain Rate n/a 53, 2017
Minimum Dew Point 1.3 °C 18:14 6.6 °C 16.1 °C, 2023 1.3 °C, 2012
Maximum Dew Point 12.8 °C 02:17 13.3 °C 18.3 °C, 2023 11.2 °C, 2020
Mean Dew Point 6.8 °C 9.9 °C 17.5 °C, 2023 6.8 °C, 2012
Measure Value Time Month cumul. Record High Record Low
Night Minimum (21-09) * 15.4 °C * 07:30 12.4 °C 19.3 °C, 2023 8.1 °C, 2020
Day Maximum (09-21) 17.4 °C 15:40 22.6 °C 25.1 °C, 2023 16.3 °C, 2013
Max 10m Temp Rise n/a 00:48 0.7 °C 1, 2016 0.3, 2018
Max 1hr Temp Rise n/a 01:17 2.8 °C 3.7, 2016 1.3, 2018
Max 1hr Hum Rise n/a 19:36 9% 20, 2015 4, 2010
Max 10m Temp Fall n/a 00:17 0.5 °C 0.9, 2016 0.2, 2010
Max 1hr Temp Fall n/a 19:41 2.0 °C 3.2, 2016 1.1, 2010
Max 1hr Hum Fall 14% 08:58 13% 28%, 2016 4%, 2018
Max 10m Wind Speed 10.0 mph 7.7 mph 14.4 mph, 2017 4.3 mph, 2014
Minimum Feels-like 11.4 °C 23:49 12.7 °C 24.6 °C, 2023 7.3 °C, 2016
Maximum Feels-like 19.5 °C 00:17 24.4 °C 30.8 °C, 2023 17.4 °C, 2013
Mean Feels-like 16.5 °C 18.8 °C 27.3 °C, 2023 14.7 °C, 2013
Air-frost Hrs 0 hrs 0 hrs 0 hrs, 2009 0 hrs, 2009
Measure Value (anomaly) Month cumul. Record High Record Low
Temperature Range 6.0 °C (-1.7) 10.6 °C (+2.5) 12.5 °C (+4.8), 2016 4.5 °C (-3.2), 2010
Humidity Range 42% 42% 51%, 2015 13%, 2019
Pressure Range 8 hPa 5 hPa 10 hPa, 2017 2 hPa, 2013
Measure Value [% of max] Month cumul. Record High Record Low
Sun Hours 6 [51%]83 hrs (147%) [63%] 11.7 [100%], 2016 0 [0%], 2014
Wet Hours 0.10.2 hrs (1%) [0.1%] 4, 2013 0, 2009
Cloud Cover am: Mostly Sunny transitioned to Partly Cloudy
pm: Partly Cloudy
Events None
Comments possible 01 Shower
Extra Comments
Issues 10th-11th, 1330-08 Data Loss (Wind: total; Other: partial). Some glitchy periods reconstructed.
Observer Absent? Yes - observations may be unreliable
Pond Temperature (Heath) 0.0 °C
Notes
Detailed daily weather report for Hampstead nw3 in London on 11th September 2012.
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

daycamsum

Wind rose