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Best time to visit · New Hampshire, United States
On the climate data, the best time to visit Portsmouth is September, scoring up to 88/100 with highs around 69°F (20°C) and 3.5 in (88 mm) of rain in September. May – August are good shoulder-season months. The toughest months are February & March and December, mainly because of cool days.
Highs run from 34°F to 74°F across the year, and the yearly total is about 52.6 in (1337 mm) of rain and snow.
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high | 34°F1°C | 35°F2°C | 40°F5°C | 49°F10°C | 58°F14°C | 67°F19°C | 74°F23°C | 74°F23°C | 69°F20°C | 58°F15°C | 48°F9°C | 40°F4°C |
| Avg low | 24°F-4°C | 25°F-4°C | 30°F-1°C | 38°F4°C | 48°F9°C | 57°F14°C | 64°F18°C | 64°F18°C | 58°F15°C | 49°F9°C | 39°F4°C | 31°F-1°C |
| Rain/snow | 4.1 in104 mm | 4.2 in107 mm | 4.8 in122 mm | 4.7 in119 mm | 4.0 in101 mm | 4.6 in116 mm | 3.6 in91 mm | 3.7 in94 mm | 3.5 in88 mm | 5.3 in135 mm | 4.6 in116 mm | 5.7 in144 mm |
| Humidity | 86% | 84% | 81% | 82% | 84% | 85% | 84% | 81% | 80% | 80% | 81% | 84% |
| Cloud | 65% | 63% | 62% | 62% | 66% | 62% | 55% | 52% | 50% | 59% | 61% | 66% |
| Comfort | 41 | 41 | 40 | 54 | 70 | 80 | 75 | 78 | 88 | 69 | 54 | 36 |
Source: NASA POWER (public domain), 2001–2025 monthly averages on a ~50 km satellite and reanalysis grid, so coasts and valleys can differ from what's shown. The grid cell sits at about 21 m (69 ft), close to Portsmouth's own ~6 m. Precipitation includes snow as melted water; daylight is calculated from latitude. Check a forecast before you go.
The coldest season, with highs of 34–40°F (1–4°C) and lows down to 24°F (-4°C). It's the wettest season, with about 14.0 in (355 mm) of rain or snow, 27% of the year's total. January & February are cold enough for snow. Comfort scores bottom out in February and December; the season averages 39/100.
Temperatures climb through the season, from 40°F highs in March to 58°F by May. About 13.5 in (342 mm) of rain falls across these months, 26% of the year's total. Nights dip below freezing in March. It holds the toughest stretch on our comfort score (March), averaging 55/100.
Peak warmth: highs of 67–74°F (19–23°C). It's the driest season, with only about 11.9 in (301 mm) of rain, 23% of the year's total. July & August feel humid, with humidity near 84%. June – August score well without being the very best (season average 78/100).
Temperatures slide from 69°F highs in September to 48°F by November. About 13.3 in (339 mm) of rain falls across these months, 25% of the year's total. Lows bottom out around 39°F (4°C). September is among the best-scoring months (season average 70/100).
By comfort score: 4 Great, 2 Good, 2 Fair and 4 Tough. Great months: June – September. Tap a month for its own guide.
On the climate data, the best time to visit Portsmouth is September, scoring up to 88/100 with highs around 69°F (20°C) and 3.5 in (88 mm) of rain in September. May – August are good shoulder-season months. The toughest months are February & March and December, mainly because of cool days.
December is the wettest month, averaging about 5.7 in (144 mm) of rain. September is the driest, with about 3.5 in (88 mm). The yearly total is around 52.6 in (1337 mm).
January is the coldest, with average lows of 24°F (-4°C) and highs of 34°F (1°C). The warmest is August, with average highs of 74°F (23°C).
Yes: in July & August humidity averages 84% with warm temperatures, so it feels muggy. Summer highs peak around 74°F (23°C).
On average, yes: lows fall below 32°F (0°C) in December – March, bottoming out around 24°F (-4°C) in January.
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