Humidity Type:
Difference?

Detailed Dew Point Data

Current
Measure Value
Dew Point 8.6 °C
Dew Pt Trend +0.2 °C /hr
24hr Mean Dew Pt 6.6 °C
Wet-Bulb Temperature 9.6 °C
Absolute Humidity 8.54 gm-3
Air Density 1234.21 gm-3
Recent Averages and Extremes
Measure Today Yesterday
Minimum 8.7 °C
00:01
5.1 °C
07:36
Maximum 8.7 °C
00:01
8.7 °C
23:56
Mean 8.7 °C
6.6 °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 (09-19)
Measure 7-day Month 31-day Year 365-day Overall Dec 8th Dec
Lowest
Min
-1.6 °C
2nd
-1.6 °C
2nd
-2.6 °C
19th
-5.6 °C
31st Jan
-5.6 °C
31st Jan
-11.5 °C
2nd Feb 2012
-9.3 °C
Day 20, 2010
-5.6 °C
2010
Highest
Max
11.0 °C
6th
11.0 °C
6th
11.8 °C
26th
21.1 °C
25th Jul
21.1 °C
25th Jul
21.1 °C
25th Jul 2019
13.5 °C
Day 19, 2015
11.8 °C
2015
Highest
Min
8.7 °C
Today
8.7 °C
Today
8.8 °C
26th
15.6 °C
26th Jul
15.6 °C
26th Jul
16.8 °C
21st Aug 2010
11.1 °C
Day 16, 2015
8.7 °C
Today
Lowest
Max
2.4 °C
2nd
2.4 °C
2nd
2.4 °C
2nd
-0.5 °C
28th Jan
-0.5 °C
28th Jan
-7.9 °C
2nd Feb 2012
-3.8 °C
Day 17, 2010
0.7 °C
2017
Lowest
Mean
0.3 °C
2nd
0.3 °C
2nd
0.3 °C
2nd
-2.3 °C
31st Jan
-2.3 °C
31st Jan
-9.7 °C
2nd Feb 2012
-5.8 °C
Day 17, 2010
-1.4 °C
2010
Highest
Mean
9.0 °C
6th
9.0 °C
6th
10.0 °C
26th
17.6 °C
26th Jul
17.6 °C
26th Jul
19.0 °C
6th Sep 2016
12.0 °C
Day 16, 2015
8.7 °C
Today
Averages                
Mean 4.7 °C 4.4 °C 4.6 °C 7.9 °C 7.7 °C 6.9 °C 4.0 °C 4.3 °C
Mean
Minimum
2.4 °C 2.1 °C 2.4 °C 5.5 °C 5.3 °C 4.3 °C 1.4 °C 1.9 °C
Mean
Maximum
6.9 °C 6.6 °C 6.6 °C 10.2 °C 10.0 °C 9.6 °C 6.5 °C 6.7 °C

Past Year Monthly Averages and Extremes (December 2018 - November 2019)
Extremes Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov
Lowest
Min
-3.5 °C
14th
-5.6 °C
31st
-3.7 °C
3rd
-3.4 °C
10th
-3.0 °C
14th
-1.9 °C
13th
3.9 °C
6th
8.2 °C
31st
6.5 °C
13th
4.1 °C
5th
0.7 °C
28th
-2.6 °C
19th
Highest
Max
12.3 °C
2nd
9.4 °C
25th
9.9 °C
16th
10.2 °C
3rd
13.4 °C
24th
16.0 °C
26th
20.2 °C
25th
21.1 °C
25th
18.7 °C
9th
17.7 °C
22nd
15.8 °C
1st
13.9 °C
1st
Highest
Min
10.3 °C
2nd
5.4 °C
26th
6.4 °C
6th
7.3 °C
15th
6.7 °C
23rd
10.9 °C
30th
15.0 °C
24th
15.6 °C
26th
15.2 °C
9th
13.5 °C
24th
10.6 °C
11th
8.8 °C
26th
Lowest
Max
0.0 °C
14th
-0.5 °C
28th
0.5 °C
2nd
4.3 °C
11th
1.9 °C
14th
3.6 °C
5th
9.8 °C
6th
12.1 °C
2nd
11.5 °C
20th
8.9 °C
8th
5.9 °C
27th
3.0 °C
20th
Lowest
Mean
-1.1 °C
14th
-2.3 °C
31st
-1.0 °C
3rd
0.6 °C
11th
-0.3 °C
14th
1.8 °C
5th
7.1 °C
6th
9.9 °C
3rd
9.3 °C
20th
6.5 °C
8th
4.0 °C
27th
1.1 °C
19th
Highest
Mean
11.7 °C
2nd
6.9 °C
13th
7.7 °C
16th
9.0 °C
15th
8.8 °C
24th
13.5 °C
30th
17.5 °C
25th
17.6 °C
26th
16.7 °C
9th
15.0 °C
24th
13.4 °C
1st
11.5 °C
1st
Averages Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov
Mean 5.8 °C 1.9 °C 4.6 °C 5.1 °C 4.9 °C 7.4 °C 11.6 °C 13.5 °C 13.5 °C 11.1 °C 8.9 °C 5.3 °C
Mean
Minimum
3.3 °C -0.4 °C 2.2 °C 2.7 °C 2.2 °C 4.5 °C 9.3 °C 11.0 °C 11.3 °C 8.3 °C 6.6 °C 3.0 °C
Mean
Maximum
8.0 °C 4.1 °C 6.8 °C 7.4 °C 7.4 °C 9.7 °C 14.0 °C 15.7 °C 15.7 °C 13.6 °C 11.2 °C 7.4 °C

Past Year Seasonal Averages
Season Daily Min Daily Max Mean
Winter 18/19 1.7 °C
6.3 °C
4.1 °C
Spring 2019 3.1 °C
8.2 °C
5.8 °C
Summer 2019 10.5 °C
15.2 °C
12.9 °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 Dec 31-day Year 365-day
Least
Humid
-5.2 °C
Ending 31st Mar 2013
-0.8 °C
Jan 2009
-0.5 °C
2010
-2.3 °C
Ending 9th Apr 2013
5.8 °C
2010
5.5 °C
Ending 18th Jul 2013
Most
Humid
16.4 °C
Ending 28th Jul 2019
13.5 °C
Jul 2019
8.3 °C
2015
14.4 °C
Ending 9th Aug 2019
7.9 °C
2019
8.1 °C
Ending 23rd Mar 2019
Lowest
Mean
Daily-Min
-7.3 °C
Ending 2nd Apr 2013
-3.3 °C
Dec 2010
-3.3 °C
2010
-4.9 °C
Ending 9th Apr 2013
3.2 °C
2010
2.9 °C
Ending 18th Jul 2013
Highest
Mean
Daily-Min
13.8 °C
Ending 28th Jul 2019
11.3 °C
Aug 2019
5.8 °C
2015
12.2 °C
Ending 11th Aug 2019
5.5 °C
2019
5.7 °C
Ending 22nd Mar 2019
Lowest
Mean
Daily-Max
-3.0 °C
Ending 31st Mar 2013
1.6 °C
Dec 2010
1.6 °C
2010
0.3 °C
Ending 9th Apr 2013
8.3 °C
2010
8.2 °C
Ending 27th Dec 2010
Highest
Mean
Daily-Max
18.9 °C
Ending 26th Jul 2019
16.1 °C
Jul 2018
10.6 °C
2015
16.9 °C
Ending 22nd Aug 2018
10.6 °C
2014
10.7 °C
Ending 3rd Dec 2014

Ranked Historical Dew Point Data

Most Humid Days
Rank Min Max Mean
1 16.8 °C
21st Aug 2010
21.1 °C
25th Jul 2019
19.0 °C
6th Sep 2016
2 16.8 °C
6th Sep 2016
20.9 °C
27th Jul 2018
17.6 °C
21st Aug 2010
3 15.7 °C
22nd Aug 2010
20.8 °C
23rd Jul 2013
17.6 °C
26th Jul 2019
4 15.7 °C
25th Aug 2016
20.2 °C
25th Jun 2019
17.5 °C
23rd Jun 2016
5 15.6 °C
20th Aug 2018
20.2 °C
24th Jul 2019
17.5 °C
25th Jun 2019
6 15.6 °C
26th Jul 2019
20.1 °C
18th Jul 2014
17.4 °C
25th Jul 2019
7 15.2 °C
9th Aug 2019
19.9 °C
28th Jun 2012
17.1 °C
23rd Jul 2013
8 15.1 °C
23rd Jun 2016
19.8 °C
28th Jun 2009
17.1 °C
25th Aug 2016
9 15.1 °C
27th Jul 2018
19.8 °C
19th Aug 2012
17.0 °C
22nd Jul 2019
10 15.1 °C
21st Aug 2018
19.8 °C
5th Sep 2016
16.9 °C
26th Jul 2018
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 11.3 °C
Aug 2019
16.1 °C
Jul 2018
13.5 °C
Jul 2019
2 11.0 °C
Jul 2019
15.7 °C
Aug 2019
13.5 °C
Jul 2018
3 10.9 °C
Aug 2018
15.7 °C
Jul 2019
13.5 °C
Aug 2019
4 10.9 °C
Jul 2018
15.7 °C
Aug 2018
13.2 °C
Aug 2018
5 10.3 °C
Sep 2016
15.4 °C
Sep 2016
13.1 °C
Sep 2016
6 10.0 °C
Aug 2009
15.4 °C
Aug 2009
12.7 °C
Aug 2009
7 9.9 °C
Sep 2014
15.2 °C
Jul 2014
12.4 °C
Jul 2014
8 9.6 °C
Aug 2012
15.1 °C
Aug 2012
12.3 °C
Aug 2012
9 9.4 °C
Jul 2009
15.1 °C
Aug 2016
12.2 °C
Sep 2014
10 9.4 °C
Aug 2016
15.0 °C
Aug 2013
12.2 °C
Aug 2016
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 December
Rank Min Max Mean
1 11.1 °C
Day 16, 2015
13.5 °C
Day 19, 2015
12.0 °C
Day 16, 2015
2 10.4 °C
Day 18, 2014
12.7 °C
Day 16, 2015
11.7 °C
Day 2, 2018
3 10.3 °C
Day 2, 2018
12.6 °C
Day 22, 2012
11.4 °C
Day 27, 2015
4 9.8 °C
Day 31, 2011
12.6 °C
Day 23, 2012
11.2 °C
Day 19, 2015
5 9.6 °C
Day 27, 2015
12.6 °C
Day 22, 2015
11.1 °C
Day 22, 2015
Least Humid Days in December
Rank Min Max Mean
1 -9.3 °C
Day 20, 2010
-3.8 °C
Day 17, 2010
-5.8 °C
Day 17, 2010
2 -8.0 °C
Day 1, 2010
-2.7 °C
Day 2, 2010
-5.3 °C
Day 1, 2010
3 -8.0 °C
Day 17, 2010
-2.1 °C
Day 1, 2010
-4.7 °C
Day 20, 2010
4 -8.0 °C
Day 19, 2010
-1.9 °C
Day 23, 2010
-4.4 °C
Day 19, 2010
5 -7.8 °C
Day 18, 2010
-1.7 °C
Day 25, 2010
-4.2 °C
Day 3, 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.