Portsmouth weather and climate in 2025
Day
23 °C
Night
13 °C
Sea
16 °C
Precipitation
47 mm
in month
Rainy days
8 days
in month
Daylight
16 hours
average
Sunshine
7 hours
average
Humidity
82 %
Day
23 °C
Night
13 °C
Sea
16 °C
Precipitation
47 mm
in month
Rainy days
8 days
in month
Daylight
16 hours
average
Sunshine
7 hours
average
Humidity
82 %
Overview: Portsmouth
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Weather overview for Portsmouth
Weather overview
Portsmouth, situated on the southern coast of the United Kingdom, experiences a maritime climate, characterized by mild temperatures throughout the year and regular rainfall. Daytime temperatures peak in July around 23 °C (73 °F), and can dip to a chillier 9 °C (47 °F) in the heart of winter. With numerous wet days each month, the city does not experience a traditional dry or wet season, as precipitation is fairly consistent, averaging around 50 mm (1.97 in) monthly. The sea temperature varies significantly, from a brisk 8 °C (46 °F) in March to a warmer 18 °C (64 °F) in August. While winds from the coast can bring a freshness to the air, the highest wind speeds are typically felt in the winter months. Sunlight hours tend to increase as the year progresses into summer, allowing for more outdoor activities.
January weather
January in Portsmouth is characterized by chilly temperatures, with an average daytime temperature of 9 °C (48 °F). Nighttime can be even colder, dipping down to 3 °C (37 °F). The sea remains quite cold at 9 °C (47 °F), feist for only the bravest swimmers! Rain showers are frequent, occurring on an average of 13 days.
February weather
As February arrives, Portsmouth's weather remains steady with daytime temperatures similar to January's at around 9 °C (47 °F). Nighttime lows average a brisk 2 °C (36 °F), while the sea temperature gently decreases to 8 °C (46 °F). Rainfall is less frequent than January, but still significant with an average of 10 days.
March weather
Moving into March, Portsmouth experiences a slight uptick in temperature with daytime highs around 11 °C (52 °F). Nights remain cool with an average low of 4 °C (39 °F). March also marks the month when the sea is at its coldest, hitting an average of 8 °C (46 °F). Rainfall occurs over approximately 11 days.
April weather
April in Portsmouth sees further improvement in weather conditions, with average daytime temperatures increasing to 14 °C (56 °F). Nighttimes are milder too, averaging 5 °C (42 °F). The sea begins to warm up, albeit slowly, with sea temperatures averaging 9 °C (48 °F). Precipitation drops slightly, with rain seen on about 10 days.
May weather
May is one of the loveliest months in Portsmouth, where daytime temperatures spring up to an average high of 17 °C (63 °F), and nights remain pleasant at around 9 °C (47 °F). The sea temperature also sees a gradual increase to 11 °C (52 °F). Lastly, rainfall continues to wane, with the occurrence of rain on an average of 9 days.
June weather
June brings the beginning of the summer warmth to Portsmouth with daytime temperatures reaching 20 °C (69 °F). Nights are comfortably warm at 11 °C (52 °F). The sea becomes more inviting, hitting an average temperature of 14 °C (57 °F). Rain, while less frequent, does make appearances on around 8 days.
July weather
July is the warmest month in Portsmouth, with the mercury climbing to an average high of 23 °C (73 °F) during the day. Nighttime temperatures are equally agreeable, averaging 13 °C (56 °F). The sea, now substantially warmer, averages 16 °C (61 °F), inviting beachgoers to take a dip. Rain is still a common, though not overbearing, feature with around 8 days of wet weather.
August weather
August in Portsmouth remains similar to July with respect to the warm daylight temperatures, averaging 22 °C (72 °F). Nights provide cool relief at around 13 °C (56 °F). The sea temperature reaches its peak this month at 18 °C (64 °F). Rainfall is slightly more frequent than in July, with about 9 days experiencing rain.
September weather
September sees the gradual transition to autumn in Portsmouth, with average daytime temperatures decreasing to 20 °C (67 °F). Nighttime cools down to 11 °C (51 °F), while the sea temperature starts to cool to 17 °C (63 °F). Rains pick up slightly with an average of 9 days experiencing precipitation.
October weather
As Portsmouth enters October, the chill in the air becomes more noticeable with an average daily high of 16 °C (60 °F). Nights get cooler with temperatures averaging 9 °C (47 °F), and the sea temperature also starts to decline to 15 °C (60 °F). Increased rainfall marks the month, averaging 12 days.
November weather
November's weather in Portsmouth is characterized by a further decrease in temperatures, with a daytime average of 12 °C (53 °F) and nights averaging 6 °C (42 °F). The sea temperature continues to cool, now averaging 13 °C (55 °F). The rain does not let up, with an average of 13 days likely to be wet.
December weather
December welcomes the onset of winter in Portsmouth with average daytime temperatures falling to 9 °C (49 °F). The nights can be notably colder with an average low of 3 °C (38 °F), while the sea retains a chill at 10 °C (51 °F). Rainfall remains consistent with an average of 13 days.
FAQs
How often does it rain in Portsmouth during January?
Rain is a common occurrence in January, with about 13 days of rainfall expected. This calls for a trusty umbrella or a reliable raincoat to be part of your daily ensemble.
Should I expect a lot of rain in Portsmouth during February?
February in Portsmouth is on the drier side compared to January, yet you can expect a fair amount of rain, typically around 10 days of the month.
Can we expect the start of spring to bring warmth in Portsmouth in March?
With the arrival of March, Portsmouth begins to thaw marginally, and you might feel the first hints of spring with daytime highs reaching about 11 °C (52 °F). However, the sea remains quite cold and might not encourage seaside activities.
Does Portsmouth get a lot of sunshine in April?
April brings better days to Portsmouth, with sunnier spells and around 6 hours of sunshine a day. This is an encouraging sign for those looking to enjoy the outdoor bloom of spring.
Is May suitable for outdoor activities in Portsmouth?
With an average high of 17 °C (63 °F) and about 7 hours of daily sunshine, May is indeed a delightful time for all manners of outdoor pursuits in Portsmouth.
How warm can we expect Portsmouth to be in June?
June in Portsmouth marks the approach of summer with pleasantly warm weather, as daytime temperatures hit an average of 20 °C (69 °F)—perfect for enjoying the longer days.
Should I expect many warm and sunny days in Portsmouth in July?
July tends to be the highlight of summer in Portsmouth, with plenty of warm and sunny days averaging around 7 hours of sunshine. The higher temperatures create a vibrant atmosphere ideal for outdoor activities.
Can we swim in the sea in Portsmouth during August?
Yes, the sea in August in Portsmouth hits its warmest at an average of 18 °C (64 °F), making it the most inviting time for a swim or water sports.
Is September a rainy month in Portsmouth?
September does see a moderate amount of rain in Portsmouth, typically over 9 days, but it's unlikely to hinder the enjoyment of early autumnal charms.
What kind of clothes should I wear in Portsmouth during October?
Layering becomes key in October in Portsmouth. Expect to don light jackets and sweaters to stay comfortable amid the daytime highs of 16 °C (60 °F) and cooler evenings.
Can I expect a lot of gray days in Portsmouth during November?
November does bring more cloud cover and damp conditions to Portsmouth, with around 13 days of rain expected, indicating that overcast skies are quite commonplace.
Is December a good month to enjoy outdoor markets in Portsmouth?
Outdoor markets in December can be quite festive in Portsmouth, although you should be prepared for cooler weather with an average high of 9 °C (49 °F) and the possibility of rain on about 13 days.
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