Humidity Type:
Difference?

Detailed Dew Point Data

Current
Measure Value
Dew Point 12.6 °C
Dew Pt Trend -0.2 °C /hr
24hr Mean Dew Pt 12.6 °C
Wet-Bulb Temperature 15.0 °C
Absolute Humidity 10.90 gm-3
Air Density 1219.72 gm-3
Recent Averages and Extremes
Measure Today Yesterday
Minimum 11.5 °C
01:56		 8.9 °C
18:29
Maximum 14.5 °C
12:56		 13.7 °C
11:08
Mean 12.7 °C
 11.2 °C
Last 6hrs LondonDew Point31-day chart of mean LondonDew Point 31-day chart of min LondonDew Point 31-day chart of max LondonDew Point
Averages, Extremes and Records
Current Station Lifetime (09-20)
Measure 7-day Month 31-day Year 365-day Overall Sep 20th Sep
Lowest
Min		 6.7 °C
17th		 5.1 °C
1st		 5.1 °C
1st		 -6.5 °C
21st Mar		 -6.5 °C
21st Mar		 -11.5 °C
2nd Feb 2012		 0.2 °C
Day 18, 2012		 3.0 °C
2012
Highest
Max		 19.4 °C
15th		 19.4 °C
15th		 19.4 °C
15th		 21.2 °C
12th Aug		 21.2 °C
12th Aug		 21.2 °C
12th Aug 2020		 19.8 °C
Day 5, 2016		 17.1 °C
2014
Highest
Min		 13.4 °C
15th		 13.9 °C
8th		 13.9 °C
8th		 17.6 °C
12th Aug		 17.6 °C
12th Aug		 17.6 °C
12th Aug 2020		 16.8 °C
Day 6, 2016		 14.3 °C
2018
Lowest
Max		 12.5 °C
18th		 10.0 °C
10th		 10.0 °C
10th		 1.0 °C
11th Feb		 1.0 °C
11th Feb		 -7.9 °C
2nd Feb 2012		 6.0 °C
Day 25, 2010		 8.3 °C
2012
Lowest
Mean		 10.0 °C
18th		 8.1 °C
1st		 7.8 °C
31st		 -2.0 °C
25th Mar		 -2.0 °C
25th Mar		 -9.7 °C
2nd Feb 2012		 3.4 °C
Day 19, 2012		 5.9 °C
2012
Highest
Mean		 16.3 °C
15th		 16.3 °C
8th		 16.3 °C
8th		 19.1 °C
12th Aug		 19.1 °C
12th Aug		 19.1 °C
12th Aug 2020		 19.0 °C
Day 6, 2016		 15.6 °C
2014
Averages                
Mean 12.7 °C 12.0 °C 12.0 °C 8.2 °C 7.9 °C 7.0 °C 10.9 °C 11.4 °C
Mean
Minimum		 10.0 °C 9.3 °C 9.7 °C 5.7 °C 5.4 °C 4.4 °C 8.3 °C 9.2 °C
Mean
Maximum		 15.2 °C 14.3 °C 14.1 °C 10.6 °C 10.2 °C 9.7 °C 13.5 °C 13.4 °C

Past Year Monthly Averages and Extremes (September 2019 - August 2020)
Extremes Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
Lowest
Min		 4.1 °C
5th		 0.7 °C
28th		 -2.6 °C
19th		 -1.6 °C
2nd		 -1.9 °C
19th		 -2.6 °C
11th		 -6.5 °C
21st		 -3.1 °C
1st		 -1.5 °C
11th		 2.3 °C
5th		 6.3 °C
7th		 5.6 °C
31st
Highest
Max		 17.7 °C
22nd		 15.8 °C
1st		 13.9 °C
1st		 11.0 °C
6th		 11.5 °C
14th		 11.4 °C
16th		 11.9 °C
10th		 11.1 °C
8th		 15.5 °C
21st		 19.0 °C
26th		 18.0 °C
31st		 21.2 °C
12th
Highest
Min		 13.5 °C
24th		 10.6 °C
11th		 8.8 °C
26th		 7.7 °C
19th		 8.1 °C
8th		 8.5 °C
15th		 8.1 °C
10th		 6.5 °C
12th		 7.9 °C
20th		 13.2 °C
25th		 13.5 °C
24th		 17.6 °C
12th
Lowest
Max		 8.9 °C
8th		 5.9 °C
27th		 3.0 °C
20th		 2.4 °C
2nd		 2.6 °C
18th		 1.0 °C
11th		 1.2 °C
29th		 2.1 °C
1st		 1.7 °C
11th		 8.8 °C
8th		 9.7 °C
21st		 10.5 °C
29th
Lowest
Mean		 6.5 °C
8th		 4.0 °C
27th		 1.1 °C
19th		 0.3 °C
2nd		 0.1 °C
19th		 -0.6 °C
11th		 -2.0 °C
25th		 0.2 °C
1st		 0.3 °C
11th		 6.1 °C
5th		 8.2 °C
21st		 7.8 °C
31st
Highest
Mean		 15.0 °C
24th		 13.4 °C
1st		 11.5 °C
1st		 9.4 °C
19th		 9.2 °C
8th		 9.8 °C
15th		 10.3 °C
10th		 8.4 °C
12th		 11.8 °C
19th		 16.4 °C
26th		 15.5 °C
25th		 19.1 °C
12th
Averages Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
Mean 11.1 °C 8.9 °C 5.3 °C 5.0 °C 5.2 °C 4.3 °C 3.1 °C 5.4 °C 6.9 °C 11.2 °C 12.2 °C 14.4 °C
Mean
Minimum		 8.3 °C 6.6 °C 3.0 °C 2.5 °C 3.1 °C 1.4 °C 0.5 °C 3.0 °C 3.8 °C 9.0 °C 9.9 °C 12.3 °C
Mean
Maximum		 13.6 °C 11.2 °C 7.4 °C 7.1 °C 7.4 °C 7.2 °C 5.4 °C 8.1 °C 9.8 °C 13.5 °C 14.3 °C 16.6 °C

Past Year Seasonal Averages
Season Daily Min Daily Max Mean
Winter 19/20 2.3 °C
 7.2 °C
 4.8 °C
Spring 2020 2.4 °C
 7.7 °C
 5.2 °C
Summer 2020 10.4 °C
 14.8 °C
 12.6 °C
Autumn 2019 6.0 °C
 10.8 °C
 8.4 °C

View daily tables of min / max / mean Dew Point data for the past year
View monthly tables of min / max / mean Dew Point data for all months in the station history.

Last 24hrs LondonDew Point 12month mean LondonDew Point 12month min LondonDew Point 12month max LondonDew Point
Record Period Averages
Measure 7-day Month Sep 31-day Year 365-day
Least
Humid		 -5.2 °C
Ending 31st Mar 2013		 -0.8 °C
Jan 2009		 8.5 °C
2012		 -2.3 °C
Ending 9th Apr 2013		 5.8 °C
2010		 5.5 °C
Ending 18th Jul 2013
Most
Humid		 18.0 °C
Ending 16th Aug 2020		 14.4 °C
Aug 2020		 13.1 °C
2016		 14.9 °C
Ending 23rd Aug 2020		 8.2 °C
2020		 8.1 °C
Ending 23rd Mar 2019
Lowest
Mean
Daily-Min		 -7.3 °C
Ending 2nd Apr 2013		 -3.3 °C
Dec 2010		 5.4 °C
2012		 -4.9 °C
Ending 9th Apr 2013		 3.2 °C
2010		 2.9 °C
Ending 18th Jul 2013
Highest
Mean
Daily-Min		 16.4 °C
Ending 16th Aug 2020		 12.3 °C
Aug 2020		 10.3 °C
2016		 12.7 °C
Ending 23rd Aug 2020		 5.7 °C
2020		 5.7 °C
Ending 22nd Mar 2019
Lowest
Mean
Daily-Max		 -3.0 °C
Ending 31st Mar 2013		 1.6 °C
Dec 2010		 11.6 °C
2012		 0.3 °C
Ending 9th Apr 2013		 8.3 °C
2010		 8.2 °C
Ending 27th Dec 2010
Highest
Mean
Daily-Max		 20.1 °C
Ending 13th Aug 2020		 16.6 °C
Aug 2020		 15.4 °C
2016		 17.2 °C
Ending 22nd Aug 2020		 10.6 °C
2020		 10.7 °C
Ending 3rd Dec 2014

Ranked Historical Dew Point Data

Most Humid Days
Rank Min Max Mean
1 17.6 °C
12th Aug 2020		 21.2 °C
12th Aug 2020		 19.1 °C
12th Aug 2020
2 17.5 °C
11th Aug 2020		 21.1 °C
25th Jul 2019		 19.0 °C
6th Sep 2016
3 16.9 °C
13th Aug 2020		 20.9 °C
27th Jul 2018		 18.8 °C
11th Aug 2020
4 16.8 °C
21st Aug 2010		 20.8 °C
23rd Jul 2013		 18.5 °C
13th Aug 2020
5 16.8 °C
6th Sep 2016		 20.8 °C
13th Aug 2020		 18.4 °C
10th Aug 2020
6 16.2 °C
10th Aug 2020		 20.7 °C
10th Aug 2020		 17.6 °C
21st Aug 2010
7 15.9 °C
15th Aug 2020		 20.6 °C
11th Aug 2020		 17.6 °C
21st Aug 2010
8 15.7 °C
22nd Aug 2010		 20.2 °C
25th Jun 2019		 17.6 °C
26th Jul 2019
9 15.7 °C
25th Aug 2016		 20.2 °C
24th Jul 2019		 17.5 °C
23rd Jun 2016
10 15.6 °C
20th Aug 2018		 20.2 °C
9th Aug 2020		 17.5 °C
25th Jun 2019
Least Humid Days
Rank Min Max Mean
1 -11.5 °C
2nd Feb 2012		 -7.9 °C
2nd Feb 2012		 -9.7 °C
2nd Feb 2012
2 -10.4 °C
7th Feb 2012		 -6.2 °C
3rd Feb 2012		 -7.8 °C
3rd Feb 2012
3 -10.3 °C
12th Mar 2013		 -5.0 °C
22nd Feb 2013		 -7.2 °C
11th Feb 2012
4 -10.2 °C
11th Feb 2012		 -5.0 °C
28th Feb 2018		 -6.9 °C
22nd Feb 2013
5 -9.5 °C
1st Feb 2009		 -4.5 °C
21st Feb 2013		 -6.9 °C
21st Feb 2013
6 -9.4 °C
25th Mar 2017		 -4.5 °C
26th Mar 2013		 -6.8 °C
28th Feb 2018
7 -9.3 °C
20th Dec 2010		 -4.4 °C
25th Mar 2013		 -6.7 °C
12th Mar 2013
8 -9.3 °C
2nd Apr 2013		 -4.1 °C
2nd Feb 2015		 -6.3 °C
7th Mar 2010
9 -9.3 °C
28th Feb 2018		 -3.8 °C
17th Dec 2010		 -6.0 °C
1st Feb 2012
10 -9.2 °C
1st Feb 2012		 -3.8 °C
28th Jan 2011		 -6.0 °C
11th Mar 2013


Most Humid Months
Rank Min Max Mean
1 12.3 °C
Aug 2020		 16.6 °C
Aug 2020		 14.4 °C
Aug 2020
2 11.3 °C
Aug 2019		 16.1 °C
Jul 2018		 13.5 °C
Jul 2019
3 11.0 °C
Jul 2019		 15.7 °C
Aug 2019		 13.5 °C
Jul 2018
4 10.9 °C
Aug 2018		 15.7 °C
Jul 2019		 13.5 °C
Aug 2019
5 10.9 °C
Jul 2018		 15.7 °C
Aug 2018		 13.2 °C
Aug 2018
6 10.3 °C
Sep 2016		 15.4 °C
Sep 2016		 13.1 °C
Sep 2016
7 10.0 °C
Aug 2009		 15.4 °C
Aug 2009		 12.7 °C
Aug 2009
8 9.9 °C
Sep 2014		 15.2 °C
Jul 2014		 12.4 °C
Jul 2014
9 9.9 °C
Jul 2020		 15.1 °C
Aug 2012		 12.3 °C
Aug 2012
10 9.6 °C
Aug 2012		 15.1 °C
Aug 2016		 12.2 °C
Sep 2014
Least Humid Months
Rank Min Max Mean
1 -3.3 °C
Dec 2010		 1.6 °C
Dec 2010		 -0.8 °C
Jan 2009
2 -3.0 °C
Mar 2013		 1.8 °C
Mar 2013		 -0.6 °C
Mar 2013
3 -2.9 °C
Feb 2013		 2.2 °C
Jan 2010		 -0.5 °C
Dec 2010
4 -2.4 °C
Feb 2018		 2.5 °C
Feb 2013		 -0.4 °C
Feb 2013
5 -2.4 °C
Jan 2017		 2.5 °C
Feb 2018		 0.0 °C
Feb 2018
6 -2.2 °C
Feb 2012		 3.0 °C
Feb 2012		 0.2 °C
Jan 2010
7 -1.7 °C
Jan 2010		 3.3 °C
Jan 2017		 0.4 °C
Jan 2017
8 -1.6 °C
Feb 2015		 4.0 °C
Feb 2015		 0.5 °C
Feb 2012
9 -1.5 °C
Feb 2016		 4.0 °C
Feb 2009		 1.5 °C
Feb 2015
10 -1.2 °C
Mar 2016		 4.1 °C
Jan 2019		 1.5 °C
Feb 2016


Most Humid Days in September
Rank Min Max Mean
1 16.8 °C
Day 6, 2016		 19.8 °C
Day 5, 2016		 19.0 °C
Day 6, 2016
2 14.7 °C
Day 19, 2014		 19.7 °C
Day 6, 2016		 16.6 °C
Day 7, 2016
3 14.7 °C
Day 13, 2016		 19.4 °C
Day 15, 2020		 16.4 °C
Day 15, 2016
4 14.6 °C
Day 9, 2011		 19.3 °C
Day 5, 2013		 16.4 °C
Day 5, 2016
5 14.3 °C
Day 20, 2018		 19.0 °C
Day 19, 2014		 16.3 °C
Day 8, 2020
Least Humid Days in September
Rank Min Max Mean
1 0.2 °C
Day 18, 2012		 6.0 °C
Day 25, 2010		 3.4 °C
Day 19, 2012
2 1.3 °C
Day 11, 2012		 6.2 °C
Day 19, 2012		 3.8 °C
Day 25, 2010
3 1.5 °C
Day 19, 2012		 6.8 °C
Day 24, 2018		 4.7 °C
Day 16, 2013
4 1.7 °C
Day 22, 2012		 7.5 °C
Day 18, 2010		 4.7 °C
Day 22, 2012
5 2.1 °C
Day 16, 2013		 7.5 °C
Day 25, 2018		 5.1 °C
Day 17, 2010

Notes:

  • Valid humidity records began in February 2009
  • All figures, unless specified, relate to the period midnight-midnight, this being when daily extremes are reset
  • 98% is the physical limit of the hygrometer (measuring RH); in reality this tends to means 100% saturation of the air. This value is achieved fairly frequently, any record with this value is just the first instance it occurred in the relevant timeframe.

The different measures of humidity:
The Dew Point (or frost point if the temperature is < 0.0 °C  is the saturation temperature of a parcel of air, i.e. the point at which water condenses out. It is the temperature at which an object would need to be for dew to form on it (dew forms because certain objects - like cars - cool more rapidly than the air, enabling them to reach the dew point). It is directly proportional to the specific humidity, and very well correlated to the absolute humidity. In everyday terms, high dew points are more uncomfortable as sweating is less effective.
Relative Humidity, on the other hand, is rather more abstract and has a very technical definition: the ratio of the partial pressure of water vapour in the air to the saturated vapour pressure of that water. The saturated vapour pressure is proportional to the air temperature, and the partial pressure indicates how much water vapour the air contains, so at a given temperature, the RH is entirely dependent on this partial pressure, making the RH useful in determining the extent to which the air is water-saturated. For example: When it rains the relative humidity will increase, but the dew point may not, as the temperature will usually fall as well. If the dew point is the same when the RH increases, the air has the same amount of water but it is cooler, so it is more saturated, as less water vapour can exist in cooler air.
Simply and concisely: Dew point is a rough measure of how much water vapour is physically in the air; relative humidity is just a measure of the degree to which the air is full of water vapour (i.e. its saturation). One is an absolute measure, the other is relative.