Climate Insights for Portsmouth

The climate in Portsmouth is hot. The average annual temperature is 26°C and approximately 1014mm of precipitation falls per year. Portsmouth receives a notable amount of rainfall throughout the year, including during its driest month. Portsmouth is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: September, October, August. The coldest months are February, March, January, when temperatures can drop to 24°C.

Portsmouth has relatively stable temperatures year-round, staying within a 4°C range. The warmest month is September, when average highs reach 28°C and the mean temperature sits around 27°C. February is the coolest month, with minimum temperatures around 24°C and an average of 25°C. Daily temperature variation is modest, with an average difference of 1°C between highs and lows.

Portsmouth is a moderately rainy area, receiving approximately 1014mm of precipitation annually, which averages out to around 84mm per month. The wettest month is November, averaging 142mm of rainfall. October and September also tend to see above-average precipitation. The driest month is February, with just 40mm. That's 101mm less than November, the wettest month. Precipitation varies noticeably between seasons, with the second half (July to December) of the year generally seeing more rainfall.

Portsmouth is very windy, with an average annual wind speed of 31km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is July, averaging 34km/h, which can feel quite blustery and may affect outdoor activities. The calmest conditions occur in September, with average winds dropping to 27km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 7km/h between the calmest and windiest months.

It is currently spring in Portsmouth, which began on March 20, 2026. Portsmouth is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in September at around 28°C, while the coldest stretch bottoms out in February near 24°C. Summer is next, beginning on June 21, 2026 — 90 days from now.

The best time to visit Portsmouth is during January, February and March, when the weather is most comfortable for travellers. During these months, average temperatures hover around 25°C with modest rainfall averaging 43mm per month. By contrast, September can be uncomfortably hot with temperatures reaching 28°C. A light rain jacket is recommended, though showers are generally brief and shouldn't disrupt your plans.

The table below shows monthly climate averages for Portsmouth based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.