Bar Harbor (Acadia) weather in September
Temperature, sea and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Excellent
Best time to visit: June – September
What is the weather like in Bar Harbor (Acadia) in September?
In September, Bar Harbor (Acadia) is mild: daytime highs average 18 °C, and nights cool down to about 14 °C. The sea averages 12.8 °C – swimming is only for the hardy. Expect around 6 hours of sunshine a day. Rain falls on about 8 days, adding up to 96 mm. All in all, September is an excellent month for a holiday in Bar Harbor (Acadia).
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 84 | 83 | 51 |
| Day | 20° | 18° | 13° |
| Night | 16° | 14° | 9° |
| Sea | 13° | 13° | 12° |
| Sun | 7 h | 6 h | 5 h |
| Rain days | 8 | 8 | 10 |
More details for September
- Daylight
- 12 h 36 min06:10 – 18:46
- UV index
- 5 · moderateclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 20 km/haverage daily peakAll months
- Cloud cover
- 55 %on averageAll months
- Hot days
- 0 days30 °C or more
- Snow days
- 0 days1 cm or more of fresh snowAll months
- Time zone
- UTC−4America/New_York
How the score comes together
- Temperatureweight 50 %100 %
- Sunshineweight 20 %57 %
- Few rainy daysweight 30 %71 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Nature escape”.
What to pack in September
- Sunscreen
- A jumper for the evenings
- Rain jacket or umbrella
Bar Harbor (Acadia) in September: quick answers
Is Bar Harbor (Acadia) hot in September?
No. In September, Bar Harbor (Acadia) is mild: daytime highs average 18 °C and nights drop to about 14 °C.
Can you swim in Bar Harbor (Acadia) in September?
Only if you don't mind cold water: in September the sea averages just 12.8 °C. Comfortable swimming temperatures are not reached at any time of year.
Does it rain much in Bar Harbor (Acadia) in September?
Rain falls on about 8 days, adding up to 96 mm.
Bar Harbor (Acadia) month by month
The whole year in Bar Harbor (Acadia)All destinations: USAWhere to go in SeptemberSea temperature in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences