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.
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- Sun hours / year
- 2,149
- Sunniest month
- July
- Peak score
- 75/100
- Rain / year
- 1,337 mm
- Snow / year
- ≈1.6 m
- Midday UV at peak
- 7 (high)
- Sea at warmest
- 18°C / 64°F
- Population
- 22k
- Elevation
- 23 m
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.
See Portsmouth on the interactive sunshine globe →
Nearby places for sunshine
- Manchester (New Hampshire) United States · 52 km · best in Sep · 2,158 h sun/yr
- Portland (Maine) United States · 76 km · best in Jul · 2,150 h sun/yr
- Boston United States · 81 km · best in Jul · 2,157 h sun/yr
- Providence/Warwick United States · 158 km · best in Aug · 2,279 h sun/yr
- Martha's Vineyard United States · 188 km · best in Jul · 2,196 h sun/yr
- Hartford United States · 199 km · best in May · 2,192 h sun/yr
Nearest destinations
- Bedford United States · 78 km · 2,157 h sun/yr · best in Jul
- Worcester United States · 125 km · 2,157 h sun/yr · best in Jul
- Lebanon United States · 134 km · 2,016 h sun/yr · best in Sep
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