The highest day temperature in September 2025 was 77°F. The lowest night temperature was 41°F. The average values for day and night temperatures during September were 67.7°F и 54.1°F respectivly.

The average sea surface temperature in September 2025 for Bar Harbor was 59.4°F. The maximum and minimum values were 57.4°F and 62.4°F respectively.

Most of the days in September are sunny but you can also expect cloudy and gloomy days.

Precipitation total in September for Bar Harbor is 1.2 in. It makes september one of the most rainy months of the year.

The average wind speed in September is 7.1 mph. It makes September one of the most windless months of the year for Bar Harbor.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Bar Harbor in September is 7.1 hours.