Annual mean 10°C · wettest around April · prevailing wind SW
Warmest
25.3 °C
Coldest
-0.7 °C
Wettest
26%
Windiest
5.0 m/s
Prevailing
SW
4.0 m/s average
When this place is good five ratings · thirty-six ten-day sections · click a cell to read it
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Every reading
bars actual · line feels-like, °Cchance of rain, %wind speed, m/ssky covered, %
The average temperature in Portsmouth over the whole year is 10°C. July is the hottest month, with highs of about 25°C; January is the coldest, with lows of about -4°C. Portsmouth has no sharply defined rainy season: the chance of rain on a given day runs from 13% in September, the driest month, to 20% in April, the wettest. Winds in Portsmouth are highest in March, averaging 4.1 m/s (15 km/h), and lightest in August, at 2.5 m/s (9 km/h). The prevailing wind is from the SW. The clearest skies in Portsmouth come in August, when the sky is typically 50% covered; April is the cloudiest month, at 60%.
Month by month Portsmouth climate by month: average temperatures year round · click a month to read it
Month
High
Low
Feels like
Chance of rain
Cloud
Wind
Being outside
Sun
Walking
January
-0°C
-4°C
-6°C
16%
58%
4.0 m/s
0
0
2
February
1°C
-3°C
-5°C
17%
55%
3.8 m/s
1
0
7
March
5°C
-1°C
-1°C
16%
56%
4.1 m/s
1
0
12
April
10°C
5°C
5°C
20%
60%
3.8 m/s
8
1
36
May
16°C
11°C
12°C
16%
60%
3.3 m/s
33
7
63
June
22°C
16°C
20°C
15%
56%
3.0 m/s
62
22
59
July
25°C
19°C
25°C
16%
51%
2.7 m/s
55
44
33
August
25°C
18°C
24°C
15%
50%
2.5 m/s
64
38
40
September
21°C
14°C
19°C
13%
51%
2.7 m/s
66
18
64
October
15°C
9°C
12°C
19%
57%
3.0 m/s
33
3
68
November
8°C
3°C
3°C
17%
50%
3.7 m/s
7
0
27
December
2°C
-2°C
-3°C
19%
55%
3.7 m/s
0
0
6
High and low are the warmest and coolest of four readings a day — midnight, 6am, noon and 6pm — so a true overnight low can sit a degree or two under them. Chance of rain, cloud and wind are the day’s average; feels-like and the three ratings (each out of 100: Good from 55, Ideal from 80) are read at midday.
Seasons, and the year in short Portsmouth weather by season
Year round, Portsmouth has days of about -0°C at their warmest in January, its coolest month, and 25°C in July, its warmest; the coolest hours of the day run from -4°C to 19°C through the year, and the average temperature over the year is 10°C around the clock. Rain is most likely around April and least likely around September. Every figure here is a decade of observations blended into one representative year, so it reads as what this date is usually like, not a forecast for one particular day.
Portsmouth weather in winterDecember to February
High 1°CLow -3°CRain 18%
Winter in Portsmouth has typical daily highs of about 1°C and lows of about -3°C, with a 18% chance of rain on a given day.
Portsmouth weather in springMarch to May
High 10°CLow 5°CRain 17%
Spring in Portsmouth has typical daily highs of about 10°C and lows of about 5°C, with a 17% chance of rain on a given day.
Portsmouth weather in summerJune to August
High 24°CLow 17°CRain 15%
Summer in Portsmouth has typical daily highs of about 24°C and lows of about 17°C, with a 15% chance of rain on a given day.
Portsmouth weather in autumnSeptember to November
High 15°CLow 8°CRain 16%
Autumn in Portsmouth has typical daily highs of about 15°C and lows of about 8°C, with a 16% chance of rain on a given day.
When is the rainy season in Portsmouth?
Portsmouth has no sharply defined rainy season: the chance of rain on a given day runs from 13% in September, the driest month, to 20% in April, the wettest.
What time of year is Portsmouth windiest?
Winds in Portsmouth are highest in March, averaging 4.1 m/s (15 km/h), and lightest in August, at 2.5 m/s (9 km/h). The prevailing wind is from the SW.
What is the average temperature in Portsmouth year round?
The average temperature in Portsmouth over the whole year is 10°C. July is the hottest month, with highs of about 25°C; January is the coldest, with lows of about -4°C.