Humidity Type:
Difference?

Detailed Relative Humidity Data

Current
Measure Value
Relative Humidity 81%
Humidity Trend -3% /hr
24hr Mean Humidity 68%
Wet-Bulb Temperature 10.9 °C
Absolute Humidity 9.00 gm-3
Air Density 1247.16 gm-3
Recent Averages and Extremes
Measure Today Yesterday
Minimum 70%
00:30
48%
13:43
Maximum 85%
05:27
90%
05:52
Mean 79%
70%
Last 6hrs  LondonHumidity31-day chart of mean LondonHumidity 31-day chart of min LondonHumidity 31-day chart of max LondonHumidity
Averages, Extremes and Records
Current Station Lifetime (09-22)
Measure 7-day Month 31-day Year 365-day Overall July 4th Jul
Lowest
Min
48%
3rd
48%
3rd
33%
16th
27%
17th Apr
27%
17th Apr
20%
9th Jun 2021
22%
Day 15, 2013
33%
2014
Highest
Max
90%
3rd
90%
1st
95%
5th
97%
13th Jan
98%
26th Dec
98%
6th Feb 2009
97%
Day 12, 2009
96%
2012
Highest
Min
70%
Today
70%
Today
81%
5th
91%
1st Mar
94%
26th Dec
98%
23rd Dec 2009
82%
Day 11, 2014
79%
2020
Lowest
Max
85%
Today
85%
Today
81%
17th
79%
27th Feb
79%
27th Feb
56%
20th Jul 2010
56%
Day 20, 2010
66%
2011
Lowest
Mean
67%
28th
70%
3rd
54%
17th
54%
17th Jun
54%
17th Jun
39%
2nd May 2013
41%
Day 15, 2013
47%
2011
Highest
Mean
79%
Today
79%
Today
91%
5th
94%
1st Mar
96%
26th Dec
98%
23rd Dec 2009
90%
Day 8, 2012
86%
2020
Averages                
Mean 73% 74% 70% 76% 80% 76% 68% 67%
Mean
Minimum
56% 56% 52% 60% 65% 60% 49% 50%
Mean
Maximum
88% 88% 89% 90% 91% 89% 85% 86%

Past Year Monthly Averages and Extremes (July 2021 - June 2022)
Extremes Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
Lowest
Min
37%
20th
53%
24th
39%
7th
60%
1st
65%
7th
69%
8th
50%
31st
46%
27th
34%
24th
27%
17th
34%
18th
33%
16th
Highest
Max
96%
26th
95%
3rd
98%
26th
98%
18th
97%
3rd
98%
26th
97%
13th
95%
26th
97%
18th
94%
14th
95%
17th
95%
5th
Highest
Min
79%
25th
76%
17th
86%
14th
85%
16th
87%
10th
94%
26th
89%
11th
84%
15th
91%
1st
70%
4th
73%
3rd
81%
5th
Lowest
Max
85%
17th
87%
16th
86%
3rd
88%
23rd
87%
21st
83%
8th
86%
23rd
79%
27th
82%
8th
82%
18th
80%
28th
81%
13th
Lowest
Mean
67%
18th
72%
11th
70%
7th
76%
24th
76%
7th
76%
8th
71%
31st
67%
27th
62%
24th
60%
17th
62%
18th
54%
17th
Highest
Mean
90%
25th
86%
22nd
93%
14th
92%
18th
92%
10th
96%
19th
92%
18th
90%
15th
94%
1st
83%
4th
83%
11th
91%
5th
Averages Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
Mean 78% 80% 82% 85% 85% 88% 85% 80% 77% 71% 74% 70%
Mean
Minimum
61% 64% 66% 72% 76% 81% 77% 67% 62% 51% 55% 51%
Mean
Maximum
91% 91% 93% 93% 92% 93% 92% 89% 89% 88% 89% 89%

Past Year Seasonal Averages
Season Daily Min Daily Max Mean
Winter 21/22 75%
92%
84%
Spring 2022 56%
89%
74%
Summer 2021 59%
90%
76%
Autumn 2021 72%
93%
84%

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

Last 24hrs  LondonHumidity 12month mean  LondonHumidity 12month min  LondonHumidity 12month max  LondonHumidity
Record Period Averages
Measure 7-day Month July 31-day Year 365-day
Least
Humid
50%
Ending 9th May 2016
60%
May 2011
61%
2013
58%
Ending 6th May 2011
73%
2016
71%
Ending 17th Jul 2017
Most
Humid
96%
Ending 27th Nov 2014
92%
Dec 2009
78%
2021
93%
Ending 20th Jan 2010
80%
2021
81%
Ending 28th Sep 2021
Lowest
Mean
Daily-Min
32%
Ending 19th Jul 2013
40%
May 2020
41%
2018
37%
Ending 21st Jul 2018
57%
2015
56%
Ending 11th Jul 2015
Highest
Mean
Daily-Min
92%
Ending 27th Nov 2014
84%
Dec 2009
61%
2021
86%
Ending 20th Jan 2010
66%
2021
67%
Ending 28th Sep 2021
Lowest
Mean
Daily-Max
73%
Ending 25th Apr 2017
76%
Apr 2017
80%
2017
76%
Ending 30th Apr 2017
85%
2016
82%
Ending 2nd Sep 2017
Highest
Mean
Daily-Max
98%
Ending 17th Jan 2010
97%
Dec 2009
91%
2021
97%
Ending 28th Dec 2009
91%
2021
92%
Ending 1st Mar 2010

Ranked Historical Humidity Data

Most Humid Days
Rank Min Max Mean
1 98%
23rd Dec 2009
98%
6th Feb 2009
98%
23rd Dec 2009
2 98%
24th Dec 2009
98%
9th Feb 2009
98%
24th Dec 2009
3 98%
30th Dec 2009
98%
10th Feb 2009
98%
30th Dec 2009
4 98%
14th Jan 2010
98%
13th Feb 2009
98%
14th Jan 2010
5 98%
15th Jan 2010
98%
7th Aug 2009
98%
15th Jan 2010
6 98%
29th Dec 2010
98%
8th Aug 2009
98%
29th Dec 2010
7 98%
22nd Oct 2012
98%
15th Sep 2009
98%
30th Dec 2010
8 98%
23rd Oct 2012
98%
16th Sep 2009
98%
20th Nov 2011
9 98%
11th Feb 2013
98%
7th Oct 2009
98%
21st Nov 2011
10 98%
8th Mar 2013
98%
10th Oct 2009
98%
22nd Oct 2012
Least Humid Days
Rank Min Max Mean
1 20%
9th Jun 2021
56%
20th Jul 2010
39%
2nd May 2013
2 21%
25th Mar 2017
56%
2nd May 2013
41%
5th May 2016
3 22%
15th Jul 2013
61%
28th Mar 2012
41%
15th Jul 2013
4 22%
18th Jul 2016
62%
6th Jan 2009
43%
20th Jul 2010
5 23%
23rd Apr 2021
63%
21st Feb 2013
43%
28th Mar 2012
6 24%
8th Sep 2012
63%
2nd Jul 2018
43%
2nd Jul 2018
7 24%
30th Jun 2015
64%
31st Jan 2009
44%
10th Jul 2015
8 24%
10th Jul 2015
65%
2nd Feb 2012
44%
1st Jul 2015
9 24%
19th Jul 2015
65%
27th May 2013
45%
17th Jul 2013
10 24%
23rd Jun 2018
65%
1st Jul 2015
45%
30th Jun 2015


Most Humid Months
Rank Min Max Mean
1 84%
Dec 2009
97%
Dec 2009
92%
Dec 2009
2 84%
Dec 2020
96%
Nov 2014
90%
Nov 2014
3 82%
Jan 2021
96%
Feb 2010
90%
Jan 2010
4 82%
Jan 2010
96%
Jan 2014
90%
Jan 2021
5 81%
Dec 2021
95%
Jan 2010
89%
Dec 2020
6 81%
Nov 2014
95%
Oct 2012
89%
Nov 2019
7 80%
Dec 2010
95%
Nov 2011
89%
Feb 2010
8 80%
Nov 2019
95%
Nov 2019
89%
Nov 2011
9 79%
Dec 2019
95%
Oct 2013
88%
Dec 2010
10 79%
Dec 2017
95%
Nov 2009
88%
Dec 2021
Least Humid Months
Rank Min Max Mean
1 40%
May 2020
76%
Apr 2017
60%
May 2011
2 41%
Jul 2018
79%
Jun 2017
60%
Apr 2017
3 42%
Jul 2013
80%
May 2011
61%
Jun 2015
4 42%
May 2011
80%
Apr 2011
61%
Jul 2013
5 42%
Jun 2015
80%
Apr 2011
62%
Apr 2011
6 43%
Jul 2014
80%
Jun 2015
62%
May 2020
7 43%
Jul 2015
80%
Jul 2017
62%
Jul 2018
8 44%
Jun 2014
81%
Jul 2010
63%
Jul 2015
9 44%
Apr 2015
82%
Jul 2015
63%
Jul 2010
10 44%
May 2015
82%
Dec 2016
63%
Jun 2017


Most Humid Days in July
Rank Min Max Mean
1 82%
Day 11, 2014
97%
Day 12, 2009
90%
Day 8, 2012
2 80%
Day 9, 2020
97%
Day 8, 2012
90%
Day 25, 2021
3 79%
Day 4, 2020
96%
Day 17, 2009
90%
Day 8, 2020
4 79%
Day 25, 2021
96%
Day 3, 2012
90%
Day 9, 2020
5 78%
Day 13, 2015
96%
Day 4, 2012
90%
Day 11, 2014
Least Humid Days in July
Rank Min Max Mean
1 22%
Day 15, 2013
56%
Day 20, 2010
41%
Day 15, 2013
2 22%
Day 18, 2016
63%
Day 2, 2018
43%
Day 20, 2010
3 24%
Day 10, 2015
65%
Day 1, 2015
43%
Day 2, 2018
4 24%
Day 19, 2015
65%
Day 11, 2015
44%
Day 10, 2015
5 27%
Day 2, 2018
66%
Day 19, 2010
44%
Day 1, 2015

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.