Humidity Type:
Difference?

Detailed Dew Point Data

Current
Measure Value
Dew Point 8.7 °C
Dew Pt Trend +0.0 °C /hr
24hr Mean Dew Pt 10.4 °C
Wet-Bulb Temperature 9.6 °C
Absolute Humidity 8.63 gm-3
Air Density 1252.02 gm-3
Recent Averages and Extremes
Measure Today Yesterday
Minimum 8.5 °C
04:59
8.3 °C
18:27
Maximum 9.2 °C
00:16
15.6 °C
08:45
Mean 8.8 °C
11.8 °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 (09-21)
Measure 7-day Month 31-day Year 365-day Overall Sep 28th Sep
Lowest
Min
8.3 °C
27th
8.2 °C
7th
8.2 °C
7th
-11.0 °C
5th Apr
-11.0 °C
5th Apr
-11.5 °C
2nd Feb 2012
0.2 °C
Day 18, 2012
4.3 °C
2018
Highest
Max
16.8 °C
26th
19.0 °C
6th
19.0 °C
6th
21.5 °C
19th Jul
21.5 °C
19th Jul
21.5 °C
19th Jul 2021
19.8 °C
Day 5, 2016
18.1 °C
2011
Highest
Min
12.1 °C
25th
15.3 °C
9th
15.3 °C
9th
15.5 °C
21st Jul
15.5 °C
21st Jul
17.6 °C
12th Aug 2020
16.8 °C
Day 6, 2016
12.6 °C
2010
Lowest
Max
9.2 °C
Today
9.2 °C
Today
9.2 °C
Today
-5.1 °C
13th Feb
-5.1 °C
13th Feb
-7.9 °C
2nd Feb 2012
6.0 °C
Day 25, 2010
9.2 °C
Today
Lowest
Mean
8.8 °C
Today
8.8 °C
Today
8.8 °C
Today
-7.2 °C
13th Feb
-7.2 °C
13th Feb
-9.7 °C
2nd Feb 2012
3.4 °C
Day 19, 2012
7.6 °C
2018
Highest
Mean
14.8 °C
25th
16.6 °C
9th
16.6 °C
9th
18.3 °C
19th Jul
18.3 °C
19th Jul
19.1 °C
12th Aug 2020
19.0 °C
Day 6, 2016
14.1 °C
2014
Averages                
Mean 12.7 °C 13.7 °C 13.5 °C 8.1 °C 7.8 °C 7.1 °C 11.0 °C 11.1 °C
Mean
Minimum
10.2 °C 11.3 °C 11.2 °C 5.7 °C 5.4 °C 4.5 °C 8.5 °C 9.0 °C
Mean
Maximum
15.0 °C 15.9 °C 15.7 °C 10.3 °C 10.1 °C 9.7 °C 13.6 °C 13.8 °C

Past Year Monthly Averages and Extremes (September 2020 - August 2021)
Extremes Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
Lowest
Min
2.0 °C
26th
3.8 °C
10th
-0.5 °C
27th
-2.9 °C
31st
-4.0 °C
25th
-8.7 °C
13th
-3.4 °C
7th
-11.0 °C
5th
-1.7 °C
8th
1.3 °C
9th
9.2 °C
16th
9.0 °C
29th
Highest
Max
19.4 °C
15th
15.3 °C
8th
15.2 °C
1st
12.2 °C
21st
10.3 °C
28th
10.9 °C
24th
11.4 °C
31st
9.4 °C
1st
14.1 °C
9th
19.7 °C
16th
21.5 °C
19th
17.7 °C
21st
Highest
Min
13.9 °C
8th
12.2 °C
30th
10.6 °C
9th
8.5 °C
18th
8.1 °C
28th
7.6 °C
20th
5.5 °C
28th
2.6 °C
9th
9.3 °C
9th
15.0 °C
17th
15.5 °C
21st
13.6 °C
22nd
Lowest
Max
7.3 °C
25th
8.6 °C
17th
5.3 °C
27th
-0.3 °C
31st
-0.1 °C
8th
-5.1 °C
13th
-0.6 °C
7th
-1.6 °C
6th
3.7 °C
7th
10.3 °C
22nd
13.6 °C
5th
13.1 °C
27th
Lowest
Mean
5.1 °C
26th
6.6 °C
10th
2.4 °C
27th
-1.4 °C
31st
-1.2 °C
25th
-7.2 °C
13th
-2.1 °C
7th
-4.0 °C
6th
1.6 °C
7th
8.8 °C
22nd
11.4 °C
29th
11.2 °C
29th
Highest
Mean
16.3 °C
8th
13.2 °C
21st
12.2 °C
9th
9.8 °C
21st
9.3 °C
28th
8.8 °C
24th
8.1 °C
31st
6.3 °C
1st
11.8 °C
9th
16.9 °C
17th
18.3 °C
19th
15.5 °C
12th
Averages Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
Mean 11.3 °C 9.2 °C 7.5 °C 4.4 °C 2.5 °C 3.2 °C 3.9 °C 1.4 °C 7.0 °C 12.9 °C 14.7 °C 13.3 °C
Mean
Minimum
8.6 °C 6.9 °C 4.7 °C 2.3 °C 0.3 °C 1.0 °C 1.4 °C -1.6 °C 4.5 °C 10.3 °C 12.4 °C 11.4 °C
Mean
Maximum
13.6 °C 11.2 °C 10.0 °C 6.3 °C 4.7 °C 5.1 °C 6.3 °C 4.1 °C 9.5 °C 15.2 °C 16.8 °C 15.4 °C

Past Year Seasonal Averages
Season Daily Min Daily Max Mean
Winter 20/21 1.2 °C
5.4 °C
3.4 °C
Spring 2021 1.4 °C
6.6 °C
4.1 °C
Summer 2021 11.4 °C
15.8 °C
13.6 °C
Autumn 2020 6.7 °C
11.6 °C
9.3 °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
14.7 °C
Jul 2021
13.7 °C
Current
14.9 °C
Ending 23rd Aug 2020
8.1 °C
2021
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
12.4 °C
Jul 2021
11.3 °C
Current
12.7 °C
Ending 23rd Aug 2020
5.7 °C
2021
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
16.8 °C
Jul 2021
15.9 °C
Current
17.2 °C
Ending 22nd Aug 2020
10.6 °C
2014
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
21.5 °C
19th Jul 2021
19.1 °C
12th Aug 2020
2 17.5 °C
11th Aug 2020
21.2 °C
12th Aug 2020
19.0 °C
6th Sep 2016
3 16.9 °C
13th Aug 2020
21.1 °C
25th Jul 2019
18.8 °C
11th Aug 2020
4 16.8 °C
21st Aug 2010
20.9 °C
27th Jul 2018
18.5 °C
13th Aug 2020
5 16.8 °C
6th Sep 2016
20.9 °C
21st Jul 2021
18.4 °C
10th Aug 2020
6 16.2 °C
10th Aug 2020
20.8 °C
23rd Jul 2013
18.3 °C
19th Jul 2021
7 15.9 °C
15th Aug 2020
20.8 °C
13th Aug 2020
17.9 °C
21st Jul 2021
8 15.7 °C
22nd Aug 2010
20.8 °C
18th Jul 2021
17.8 °C
20th Jul 2021
9 15.7 °C
25th Aug 2016
20.7 °C
10th Aug 2020
17.6 °C
21st Aug 2010
10 15.6 °C
20th Aug 2018
20.6 °C
11th Aug 2020
17.6 °C
21st Aug 2010
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 -11.0 °C
5th Apr 2021
-6.2 °C
3rd Feb 2012
-7.8 °C
3rd Feb 2012
3 -10.4 °C
7th Feb 2012
-5.1 °C
13th Feb 2021
-7.2 °C
13th Feb 2021
4 -10.3 °C
12th Mar 2013
-5.0 °C
22nd Feb 2013
-7.2 °C
11th Feb 2012
5 -10.2 °C
11th Feb 2012
-5.0 °C
28th Feb 2018
-6.9 °C
22nd Feb 2013
6 -9.5 °C
1st Feb 2009
-4.5 °C
21st Feb 2013
-6.9 °C
21st Feb 2013
7 -9.4 °C
25th Mar 2017
-4.5 °C
26th Mar 2013
-6.8 °C
28th Feb 2018
8 -9.3 °C
20th Dec 2010
-4.4 °C
25th Mar 2013
-6.7 °C
12th Mar 2013
9 -9.3 °C
2nd Apr 2013
-4.3 °C
12th Feb 2021
-6.3 °C
7th Mar 2010
10 -9.3 °C
28th Feb 2018
-4.1 °C
2nd Feb 2015
-6.0 °C
1st Feb 2012


Most Humid Months
Rank Min Max Mean
1 12.4 °C
Jul 2021
16.8 °C
Jul 2021
14.7 °C
Jul 2021
2 12.3 °C
Aug 2020
16.6 °C
Aug 2020
14.4 °C
Aug 2020
3 11.4 °C
Aug 2021
16.1 °C
Jul 2018
13.7 °C
Current
4 11.3 °C
Aug 2019
15.9 °C
Current
13.5 °C
Jul 2019
5 11.3 °C
Current
15.7 °C
Aug 2019
13.5 °C
Jul 2018
6 11.0 °C
Jul 2019
15.7 °C
Jul 2019
13.5 °C
Aug 2019
7 10.9 °C
Aug 2018
15.7 °C
Aug 2018
13.3 °C
Aug 2021
8 10.9 °C
Jul 2018
15.4 °C
Sep 2016
13.2 °C
Aug 2018
9 10.3 °C
Jun 2021
15.4 °C
Aug 2009
13.1 °C
Sep 2016
10 10.3 °C
Sep 2016
15.4 °C
Aug 2021
12.9 °C
Jun 2021
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
Apr 2021
4.0 °C
Feb 2015
0.5 °C
Feb 2012
9 -1.6 °C
Feb 2015
4.0 °C
Feb 2009
1.4 °C
Apr 2021
10 -1.5 °C
Feb 2016
4.1 °C
Jan 2019
1.5 °C
Feb 2015


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 15.3 °C
Day 9, 2021
19.7 °C
Day 6, 2016
16.6 °C
Day 9, 2021
3 15.2 °C
Day 10, 2021
19.4 °C
Day 15, 2020
16.6 °C
Day 7, 2016
4 14.7 °C
Day 19, 2014
19.3 °C
Day 5, 2013
16.4 °C
Day 15, 2016
5 14.7 °C
Day 13, 2016
19.0 °C
Day 19, 2014
16.4 °C
Day 5, 2016
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
7.3 °C
Day 25, 2020
4.7 °C
Day 22, 2012
5 2.0 °C
Day 26, 2020
7.5 °C
Day 18, 2010
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.