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.