The highest day temperature in September 2025 was 88°F. The lowest night temperature was 47°F. The average values for day and night temperatures during September were 75.0°F и 61.4°F respectivly.

The average sea surface temperature in September 2025 for Boston was 65.3°F. The maximum and minimum values were 61.2°F and 68.6°F respectively.

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

Precipitation total in September for Boston is 1.6 in. It makes september the least rainy month of the year.

The average wind speed in September is 8.0 mph. It makes September one of the most windless months of the year for Boston.

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 Boston in September is 7.5 hours.