Humidity Type:
Difference?

Detailed Dew Point Data

Current
Measure Value
Dew Point 2.5 °C
Dew Pt Trend +0.5 °C /hr
24hr Mean Dew Pt 3.4 °C
Wet-Bulb Temperature 4.7 °C
Absolute Humidity 5.70 gm-3
Air Density 1243.66 gm-3
Recent Averages and Extremes
Measure Today Yesterday
Minimum 0.6 °C
08:18		 4.0 °C
23:37
Maximum 4.5 °C
00:59		 6.9 °C
13:42
Mean 2.0 °C
 5.6 °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 (09-20)
Measure 7-day Month 31-day Year 365-day Overall Jan 28th Jan
Lowest
Min		 0.6 °C
Today		 -1.9 °C
19th		 -1.9 °C
21st		 -1.9 °C
19th Jan		 -5.6 °C
31st Jan		 -11.5 °C
2nd Feb 2012		 -8.5 °C
Day 21, 2017		 -6.5 °C
2011
Highest
Max		 8.2 °C
26th		 11.5 °C
14th		 11.5 °C
14th		 11.5 °C
14th Jan		 21.1 °C
25th Jul		 21.1 °C
25th Jul 2019		 13.2 °C
Day 9, 2015		 10.3 °C
2018
Highest
Min		 5.3 °C
26th		 8.1 °C
8th		 8.1 °C
8th		 8.1 °C
8th Jan		 15.6 °C
26th Jul		 16.8 °C
21st Aug 2010		 10.5 °C
Day 13, 2011		 7.6 °C
2018
Lowest
Max		 4.5 °C
Today		 2.6 °C
18th		 2.6 °C
18th		 2.6 °C
18th Jan		 0.1 °C
31st Jan		 -7.9 °C
2nd Feb 2012		 -3.8 °C
Day 28, 2011		 -3.8 °C
2011
Lowest
Mean		 2.0 °C
Today		 0.1 °C
19th		 0.1 °C
19th		 0.1 °C
19th Jan		 -2.3 °C
31st Jan		 -9.7 °C
2nd Feb 2012		 -5.6 °C
Day 28, 2011		 -5.6 °C
2011
Highest
Mean		 6.8 °C
26th		 9.2 °C
8th		 9.2 °C
8th		 9.2 °C
8th Jan		 17.6 °C
26th Jul		 19.0 °C
6th Sep 2016		 11.7 °C
Day 24, 2016		 8.8 °C
2018
Averages                
Mean 4.9 °C 5.1 °C 5.1 °C 5.1 °C 8.0 °C 6.9 °C 2.5 °C 1.9 °C
Mean
Minimum		 3.4 °C 3.0 °C 3.0 °C 3.0 °C 5.5 °C 4.3 °C 0.2 °C -0.1 °C
Mean
Maximum		 6.2 °C 7.2 °C 7.2 °C 7.2 °C 10.3 °C 9.6 °C 5.4 °C 4.8 °C

Past Year Monthly Averages and Extremes (January 2019 - December 2019)
Extremes Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Lowest
Min		 -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		 -1.6 °C
2nd
Highest
Max		 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		 11.0 °C
6th
Highest
Min		 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		 7.7 °C
19th
Lowest
Max		 -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		 2.4 °C
2nd
Lowest
Mean		 -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		 0.3 °C
2nd
Highest
Mean		 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		 9.4 °C
19th
Averages Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Mean 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 5.0 °C
Mean
Minimum		 -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 2.5 °C
Mean
Maximum		 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 7.1 °C

Past Year Seasonal Averages
Season Daily Min Daily Max Mean
Winter 18/19 1.4 °C
 6.0 °C
 3.8 °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 Jan 31-day Year 365-day
Least
Humid		 -5.2 °C
Ending 31st Mar 2013		 -0.8 °C
Jan 2009		 -0.8 °C
2009		 -2.3 °C
Ending 9th Apr 2013		 5.1 °C
2020		 5.5 °C
Ending 18th Jul 2013
Most
Humid		 16.4 °C
Ending 28th Jul 2019		 13.5 °C
Jul 2019		 5.1 °C
Current		 14.4 °C
Ending 9th Aug 2019		 7.8 °C
2018		 8.1 °C
Ending 23rd Mar 2019
Lowest
Mean
Daily-Min		 -7.3 °C
Ending 2nd Apr 2013		 -3.3 °C
Dec 2010		 -2.4 °C
2017		 -4.9 °C
Ending 9th Apr 2013		 3.0 °C
2020		 2.9 °C
Ending 18th Jul 2013
Highest
Mean
Daily-Min		 13.8 °C
Ending 28th Jul 2019		 11.3 °C
Aug 2019		 3.0 °C
Current		 12.2 °C
Ending 11th Aug 2019		 5.3 °C
2018		 5.7 °C
Ending 22nd Mar 2019
Lowest
Mean
Daily-Max		 -3.0 °C
Ending 31st Mar 2013		 1.6 °C
Dec 2010		 2.2 °C
2010		 0.3 °C
Ending 9th Apr 2013		 7.2 °C
2020		 8.2 °C
Ending 27th Dec 2010
Highest
Mean
Daily-Max		 18.9 °C
Ending 26th Jul 2019		 16.1 °C
Jul 2018		 8.0 °C
2014		 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 January
Rank Min Max Mean
1 10.5 °C
Day 13, 2011		 13.2 °C
Day 9, 2015		 11.7 °C
Day 24, 2016
2 9.0 °C
Day 3, 2013		 13.2 °C
Day 24, 2016		 11.3 °C
Day 13, 2011
3 8.1 °C
Day 8, 2020		 12.3 °C
Day 29, 2013		 10.2 °C
Day 29, 2013
4 8.0 °C
Day 24, 2016		 12.0 °C
Day 13, 2011		 9.6 °C
Day 27, 2016
5 7.6 °C
Day 28, 2018		 11.9 °C
Day 6, 2014		 9.5 °C
Day 3, 2013
Least Humid Days in January
Rank Min Max Mean
1 -8.5 °C
Day 21, 2017		 -3.8 °C
Day 28, 2011		 -5.6 °C
Day 28, 2011
2 -7.8 °C
Day 19, 2016		 -2.8 °C
Day 29, 2011		 -5.1 °C
Day 21, 2017
3 -7.6 °C
Day 22, 2017		 -2.5 °C
Day 26, 2017		 -5.0 °C
Day 18, 2017
4 -6.8 °C
Day 18, 2017		 -2.3 °C
Day 9, 2010		 -4.9 °C
Day 19, 2016
5 -6.7 °C
Day 17, 2013		 -2.3 °C
Day 18, 2013		 -4.6 °C
Day 30, 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.