The highest day temperature in September 2025 was 91°F. The lowest night temperature was 46°F. The average values for day and night temperatures during September were 80.3°F и 60.2°F respectivly.

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

Precipitation total in September for Harpers Ferry is 1.0 in. It makes september one of the most rainy months of the year.

The average wind speed in September is 5.6 mph. It makes September one of the most windless months of the year for Harpers Ferry.

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 Harpers Ferry in September is 7.5 hours.