Portsmouth weather by month & the best time to visit
United States · seaside town · oceanic / maritime climate
The best time to visit Portsmouth is July — its sunniest month (Sunshine Score 75/100), with September and August close behind. Portsmouth averages about 2,149 hours of sunshine a year. Daytime highs around 23°C / 73°F and roughly 91 mm of rain in July.
When is the best time to visit Portsmouth?
For sunshine, the best time to visit Portsmouth is July, then September and August. The dullest month is January (0/100, 104 mm of rain). The full month-by-month picture is in the table below.
How sunny is Portsmouth?
Portsmouth gets a moderate 2,149 hours of sunshine a year. 75 Sunshine Score points separate July (75) from January (0), so the month you pick matters. It ranks #346 of 580 destinations in United States for annual sunshine, below the national median of 2,279 hours. The year's 1,337 mm of rain spreads fairly evenly across the months, with no pronounced dry season.
Sunshine Score by month
| Month | Score | Day high | Night low | Rain | UV | Sea |
|---|---|---|---|---|---|---|
| January | 0 | 1° / 34°F | -4° / 25°F | 104 mm | 1 | 5° / 41°F |
| February | 0 | 2° / 36°F | -4° / 25°F | 107 mm | 2 | 4° / 39°F |
| March | 0 | 4° / 39°F | -1° / 30°F | 122 mm | 3 | 5° / 41°F |
| April | 6 | 9° / 48°F | 3° / 37°F | 119 mm | 4 | 7° / 45°F |
| May | 36 | 14° / 57°F | 9° / 48°F | 101 mm | 5 | 11° / 52°F |
| June | 64 | 19° / 66°F | 14° / 57°F | 116 mm | 6 | 16° / 61°F |
| July | 75 | 23° / 73°F | 18° / 64°F | 91 mm | 7 | 17° / 63°F |
| August | 74 | 23° / 73°F | 18° / 64°F | 94 mm | 6 | 18° / 64°F |
| September | 75 | 20° / 68°F | 14° / 57°F | 88 mm | 5 | 18° / 64°F |
| October | 33 | 14° / 57°F | 9° / 48°F | 135 mm | 3 | 14° / 57°F |
| November | 6 | 9° / 48°F | 4° / 39°F | 116 mm | 1 | 10° / 50°F |
| December | 0 | 4° / 39°F | -1° / 30°F | 144 mm | 1 | 7° / 45°F |
Sea temperature in Portsmouth by month
The sea off Portsmouth is warmest in August at around 18°C / 64°F, and coolest in February at 4°C / 39°F. It never reaches comfortable swimming temperatures (21°C+). Month-by-month sea-surface temperatures are in the Sea column of the table above.
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Portsmouth: questions and answers
What kind of destination is Portsmouth?
Portsmouth is a seaside town in United States with a oceanic / maritime climate — the sea reaches 18°C at its warmest.
How many hours of sunshine does Portsmouth get a year?
Portsmouth gets about 2,149 hours of sunshine a year, at its best around July.
When is the best time to visit Portsmouth?
The sunniest time to visit Portsmouth is July, when the Sunshine Score peaks at 75/100 (with September and August close behind). Expect daytime highs around 23°C / 73°F.
What is the least sunny month in Portsmouth?
January is the least sunny month in Portsmouth, scoring 0/100 with about 104 mm of rain.
What is the sea temperature in Portsmouth?
The sea in Portsmouth ranges from about 4°C (February) to 18°C (August). Month-by-month sea temperatures are on this page.
How strong is the sun in Portsmouth?
The typical midday UV index in Portsmouth peaks around 7 (high) in July, easing to about 1 (low) in January. Month-by-month midday UV values are in the UV column of the table on this page.
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