Measure | Value (anomaly) | Time |
Month cumul. | Record High | Record Low |
Minimum Temperature |
5.6 °C (-0.3) |
06:05 |
6.2 °C (+0.5) |
12.1 °C (+6.2), 2024 |
-0.6 °C (-6.5), 2021 |
Maximum Temperature |
17.3 °C (+3.1) |
14:42 |
14.1 °C (+0.4) |
20.8 °C (+6.6), 2024 |
8.8 °C (-5.4), 2019 |
Mean Temperature |
11.7 °C (+1.4) |
|
10.0 °C (+0.4) |
15.7 °C, 2024 |
4.8 °C, 2019 |
Minimum Humidity |
39% |
14:33 |
46% |
78%, 2018 |
39%, 2016 |
Maximum Humidity |
86% |
07:34 |
87% |
97%, 2009 |
71%, 2017 |
Mean Humidity |
54% |
|
67% |
87%, 2013 |
54%, 2016 |
Minimum Pressure |
1007 hPa |
04:09 |
1006 hPa |
1032 hPa, 2021 |
995 hPa, 2023 |
Maximum Pressure |
1010 hPa |
22:39 |
1010 hPa |
1034 hPa, 2021 |
1006 hPa, 2012 |
Mean Pressure |
1006 hPa |
|
1007 hPa |
1034 hPa, 2021 |
1002 hPa, 2023 |
Mean Wind Speed |
1.5 mph (-3.4) |
|
4.1 mph (-0.8) |
9.6 mph, 2020 |
1.5 mph, 2016 |
Maximum Wind Speed |
9.0 mph |
13:33 |
11.9 mph |
19.4 mph, 2020 |
7.4 mph, 2012 |
Maximum Gust |
13.0 mph |
13:19 |
19.1 mph |
27.6 mph, 2020 |
10.0 mph, 2012 |
Mean Wind Direction |
NW |
|
|
|
|
Rainfall |
0.0 mm |
|
15.6 mm (86%) |
6.5 mm, 2013 |
|
Maximum Hourly Rain |
n/a |
|
|
2.1, 2013 |
|
Maximum 10-min Rain |
n/a |
|
|
1.2, 2012 |
|
Maximum Rain Rate |
n/a |
|
|
17, 2013 |
|
Minimum Dew Point |
3.1 °C |
14:18 |
1.4 °C |
9.1 °C, 2022 |
-4.2 °C, 2021 |
Maximum Dew Point |
7.5 °C |
23:55 |
7.4 °C |
13.4 °C, 2024 |
2.9 °C, 2011 |
Mean Dew Point |
4.4 °C |
|
3.9 °C |
11.0 °C, 2024 |
-0.5 °C, 2021 |
Measure | Value | Time |
Month cumul. | Record High | Record Low |
Night Minimum (21-09) |
5.6 °C |
06:05 |
6.4 °C |
12.2 °C, 2024 |
-0.6 °C, 2021 |
Day Maximum (09-21) |
* 17.6 °C * |
14:42 |
14.2 °C |
20.8 °C, 2024 |
8.8 °C, 2019 |
Max 10m Temp Rise |
0.5 °C |
08:00 |
0.6 °C |
1.2 °C, 2021 |
0.3 °C, 2018 |
Max 1hr Temp Rise |
3.2 °C |
09:02 |
2.5 °C |
5.1 °C, 2021 |
1.3 °C, 2018 |
Max 1hr Hum Rise |
12% |
20:37 |
11% |
25%, 2023 |
3%, 2017 |
Max 10m Temp Fall |
0.7 °C |
20:30 |
0.6 °C |
1.3 °C, 2019 |
0.2 °C, 2018 |
Max 1hr Temp Fall |
1.8 °C |
20:55 |
1.7 °C |
2.7 °C, 2019 |
0.7 °C, 2018 |
Max 1hr Hum Fall |
17% |
10:23 |
16% |
25%, 2019 |
5%, 2018 |
Max 10m Wind Speed |
6.7 mph |
14:33 |
9.1 mph |
14.5 mph, 2020 |
6.1 mph, 2012 |
Minimum Feels-like |
4.0 °C |
05:00 |
3.8 °C |
12.9 °C, 2024 |
-2.9 °C, 2019 |
Maximum Feels-like |
17.6 °C |
14:33 |
14.2 °C |
22.8 °C, 2024 |
8.6 °C, 2019 |
Mean Feels-like |
10.0 °C |
|
9.2 °C |
17.4 °C, 2024 |
2.5 °C, 2019 |
Air-frost Hrs |
0 hrs |
|
0 hrs |
5 hrs, 2021 |
0 hrs, 2009 |
Measure | Value (anomaly) |
Month cumul. | Record High | Record Low |
Temperature Range |
11.7 °C (+3.4) |
8.0 °C (-0.1) |
12.5 °C (+4.2), 2021 |
5.6 °C (-2.7), 2018 |
Humidity Range |
47% |
41% |
55%, 2012 |
17%, 2018 |
Pressure Range |
3 hPa |
4 hPa |
13 hPa, 2020 |
2 hPa, 2012 |
Measure | Value [% of max] |
Month cumul. | Record High | Record Low |
Sun Hours |
8 [65%] | 57 hrs (84%) [36%] |
12.2 [98%], 2014 |
0 [0%], 2018 |
Wet Hours |
0 | 22 hrs (110%) [7.1%] |
7, 2013 |
0, 2010 |
Cloud Cover |
am: Sunny transitioned to Mostly Sunny pm: Partly Cloudy transitioned to Mostly Cloudy |
Events |
None |
Comments |
- |
Extra Comments |
|
Issues |
No data all day. Harpenden wind data, UCL for others. T/H CORRECTED |
Observer Absent? |
Yes - observations may be unreliable |
Pond Temperature (Heath) |
0.0 °C |