The highest day temperature in September 2025 was 80°F. The lowest night temperature was 48°F. The average values for day and night temperatures during September were 67.1°F и 57.6°F respectivly.

The average sea surface temperature in September 2025 for Harbor Springs was 66.9°F. The maximum and minimum values were 65.2°F and 69.8°F respectively.

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

Precipitation total in September for Harbor Springs is 0.7 in. It makes september one of the least rainy months of the year.

The average wind speed in September is 7.9 mph. It makes September one of the most windless months of the year for Harbor Springs.

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 Harbor Springs in September is 7.4 hours.