Bar Harbor Weather in September
Bar Harbor in September averages 21°C (70°F) during the day and 11°C (52°F) at night. Keep in mind that quite a bit of rainfall is expected this month.
Rainfall in Bar Harbor in September
Analyzing past climate data, one can expect approximately 10 days of rain, averaging 102 mm (4 in). The rain this month tends to fall in heavier spells rather than light drizzle. When it rains, showers can be significant.
Temperature in Bar Harbor in September
September in Bar Harbor brings typical temperatures with highs around 21°C (70°F) and lows of 11°C (52°F). A light jacket or extra layer can be useful, especially outside the warmest hours of the day. With overnight lows of 11°C (52°F), evenings can feel noticeably cooler than the daytime. An extra layer is a good idea, though the cool air makes for a good night's sleep.If you prefer enjoying temperate temperatures and rain-free days, July and August typically offer the best circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our Bar Harbor's climate page.
Bar Harbor Temperature in September
Min Temperature
11°C (52°F)
Max Temperature
21°C (70°F)
Chance of Rain
33%
Precipitation
102 mm (4 in)
Rainy days
10 days
Daily Historical Temperatures
47-year average (1976-2025)
Based on our historical records, temperatures in Bar Harbor typically drop from around 22°C (72°F) at the start of September to approximately 18°C (64°F) by the end. Nights are cool, with lows typically ranging from 8°C (46°F) to 12°C (54°F).
Average temperatures in September
Historical weather for Bar Harbor in September
Browse day-by-day weather records for Bar Harbor spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Bar Harbor historical weather extremes in September
Based on weather observations in Bar Harbor between 1997 and 2025, these are the recorded extremes during September.
- The warmest day in September was on September 3, 1999, with a maximum of 33°C (91°F).
- The lowest daytime temperature in September was 9°C (48°F), recorded on September 21, 1997.
- Bar Harbor registered its coldest September night on September 21, 2020, with temperatures dropping to -1°C (30°F).
Best Places in the United States of America in September
Find out more about the weather in the United States of America and which places have the best travel conditions in this month. See all of the United States of America in September →
perfect weather
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tolerable
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What to Wear in Bar Harbor in September
For Bar Harbor in September, you'll want flexible clothing. It's wise to pack cotton shirts, comfortable shorts, and a pair of jeans for cooler evenings. A light sweater or jacket is useful for air-conditioned spaces (like buses) or unexpected cool moments. High rain levels are expected, so pack waterproof gear and an umbrella or poncho.What To Do in Bar Harbor in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our Bar Harbor's climate page.
See the full Bar Harbor climate overview or explore weather in the United States of America.
