Early autumn · Weather & things to do
Portsmouth in September
Portsmouth sees its driest month, with just 3.5 in (88 mm) of rain, highs of 69°F (20°C) and lows of 58°F (15°C).
September opens the best stretch on our comfort score, at 88/100 (the top score of the year).
- Avg high
- 69°F (20°C)
- Avg low
- 58°F (15°C)
- Rain
- 3.5 in (88 mm)
- Humidity
- 80%
- Cloud cover
- 50%
- Daylight
- ~12 h 17 min
- Comfort score
- 88/100 · Great
What September feels like
Highs near 69°F (20°C) make for comfortable sightseeing weather.
Lows average 58°F (15°C).
Showers are part of the month, adding up to about 3.5 in (88 mm).
Plan around September
September is one of Portsmouth's best months on the climate data.
- Opens the best-scoring stretch on our comfort score: September.
- Comfort improves from 78/100 in August to 88/100.
- September sits inside the May – Oct window our Boston to Portland route recommends.
What to pack for September
- A warm layer for eveningsnights drop to 58°F
- Packable rain jacket or umbrellaabout 3.5 in of rain
- Comfortable walking shoesmost places below are best reached on foot or with short walks
What to do in Portsmouth in September
With conditions on your side, the picks below favor time outside.
The Black Trumpet
Bistro and upstairs wine bar in an old waterfront building.
Why now September scores 88/100 for comfort, good conditions for being outside.
Odiorne Point State Park
Rocky shoreline trails and tide pools, plus the Seacoast Science Center.
Why now Highs near 69°F and 3.5 in of monthly rain make this an easy outdoor pick.
Strawbery Banke Museum
Ten acres of restored houses spanning 300 years of a waterfront neighborhood.
Why now Our curated notes say it's best May–Oct.
The Press Room
Longest-running bar and live-music room in downtown Portsmouth: jazz, blues and local bands in a brick basement pub.
Moxy
Chef Matt Louis's American tapas using New England ingredients.
Nearby in September
- New Hampshire in September~42 mi · highs 74°F, 3.7 in rain · 3°C (6°F) warmer by day, about as wet
- Portland, Maine in September~48 mi · highs 65°F, 3.8 in rain · 2°C (3°F) cooler by day, about as wet
- Boston in September~51 mi · highs 75°F, 3.6 in rain · 4°C (7°F) warmer by day, about as wet
- White Mountains in September~87 mi · highs 50°F, 3.6 in rain · 10°C (19°F) cooler by day, about as wet
NASA POWER 2001–2025 monthly averages on a ~50 km grid. Comfort scores weigh temperature, rain, humidity and cloud: see how we score each month. Check a forecast before you go.
Portsmouth in September: quick answers
Is September a good time to visit Portsmouth?
Yes. On the climate data it's one of the best months, scoring 88/100. Expect highs of 69°F (20°C) and 3.5 in (88 mm) of rain. September is inside the May – Oct window our Boston to Portland route recommends.
How hot is Portsmouth in September?
Average highs are 69°F (20°C) and average lows 58°F (15°C), making it the 3rd-warmest month by daytime highs.
Does it rain a lot in Portsmouth in September?
Some: about 3.5 in (88 mm) of rain falls across September on average, the driest month of the year. The annual total is about 52.6 in (1337 mm).
What should I pack for Portsmouth in September?
Bring a warm layer for evenings (nights drop to 58°F), packable rain jacket or umbrella (about 3.5 in of rain) and comfortable walking shoes (most places below are best reached on foot or with short walks).
Routes in season in September
- Boston to Portland May – Oct
Planning Portsmouth in September?
Plan it together in TripsCircle: one itinerary, one shared packing list and costs split as you go.