The weather in Portsmouth in September is hot. The average temperatures are between 21°C and 27°C.
You can expect about 3 to 8 days of rain in Portsmouth during the month of September. It’s a good idea to bring along your umbrella so that you don’t get caught in poor weather.
Our weather forecast can give you a great sense of what weather to expect in Portsmouth in September 2025.
If you’re planning to visit Portsmouth in the near future, we highly recommend that you review the 14 day weather forecast for Portsmouth before you arrive.
Temperatures
27° / 21°
Rainy Days
5
Snowy Days
0
Dry Days
25
Rainfall
155
mm
Sun Hours
10.5
Hrs