Early autumn · Weather & things to do
Portland, Maine in September
Portland, Maine cools off: highs slip to 65°F (18°C), from 70°F in August, with lows of 58°F (15°C) and about 3.8 in (97 mm) of rain.
September opens the best stretch on our comfort score, at 87/100 (the top score of the year).
- Avg high
- 65°F (18°C)
- Avg low
- 58°F (15°C)
- Rain
- 3.8 in (97 mm)
- Humidity
- 83%
- Cloud cover
- 50%
- Daylight
- ~12 h 17 min
- Comfort score
- 87/100 · Great
What September feels like
Highs near 65°F (18°C) make for comfortable sightseeing weather.
After dark, temperatures fall to about 58°F (15°C).
Showers are part of the month, adding up to about 3.8 in (97 mm).
Plan around September
September is one of Portland, Maine's best months on the climate data.
- Opens the best-scoring stretch on our comfort score: September.
- Comfort improves from 74/100 in August to 87/100.
- September sits inside the May – Oct window our Boston to Portland route recommends.
What to pack for September
- A warm layer for eveningslows near 58°F
- Packable rain jacket or umbrellaa shower or two is likely
- Comfortable walking shoesmost picks involve some walking
What to do in Portland, Maine in September
September is good outdoor weather here, so these picks lean toward the open air.
Portland Head Light
Maine's oldest lighthouse (1791) on cliffs in Fort Williams Park.
Why now September scores 87/100 for comfort, good conditions for being outside.
Portland Museum of Art
Strong Winslow Homer and Maine art collection in the Arts District.
Allagash Brewing Company
Belgian-style brewery with a tasting room and free tours.
The Holy Donut
Maine potato donuts in flavors like dark chocolate sea salt.
Eastern Promenade
Hilltop park and trail with views over Casco Bay and its islands.
Why now Highs near 65°F and 3.8 in of monthly rain make this an easy outdoor pick.
Nearby in September
- Portsmouth in September~48 mi · highs 69°F, 3.5 in rain · 2°C (3°F) warmer by day, about as wet
- Maine in September~51 mi · highs 72°F, 3.5 in rain · 4°C (6°F) warmer by day, about as wet
- White Mountains in September~67 mi · highs 50°F, 3.6 in rain · 8°C (15°F) cooler by day, about as wet
- New Hampshire in September~73 mi · highs 74°F, 3.7 in rain · 5°C (9°F) warmer 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.
Portland, Maine in September: quick answers
Is September a good time to visit Portland, Maine?
Yes. On the climate data it's one of the best months, scoring 87/100. Expect highs of 65°F (18°C) and 3.8 in (97 mm) of rain. September is inside the May – Oct window our Boston to Portland route recommends.
How hot is Portland, Maine in September?
Average highs are 65°F (18°C) and average lows 58°F (15°C), making it the 3rd-warmest month by daytime highs.
Does it rain a lot in Portland, Maine in September?
Some: about 3.8 in (97 mm) of rain falls across September on average, the 3rd-driest month of the year. The annual total is about 53.7 in (1363 mm).
What should I pack for Portland, Maine in September?
Bring a warm layer for evenings (lows near 58°F), packable rain jacket or umbrella (a shower or two is likely) and comfortable walking shoes (most picks involve some walking).
More on Portland, Maine
Routes in season in September
- Boston to Portland May – Oct
Planning Portland, Maine in September?
Bring the crew into one shared trip: vote on dates, build the day-by-day plan, split costs and share one packing list.