The highest day temperature in September 2026 was 73°F. The lowest night temperature was 49°F. The average values for day and night temperatures during September were 67.0°F и 56.3°F respectivly.

The average sea surface temperature in September 2026 for Plymouth was 65.3°F. The maximum and minimum values were 63.8°F and 67.2°F respectively.

You can expect various weather conditions during September. Be ready for sunny, cloudy or even gloomy days.

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

The average wind speed in September is 11.4 mph. It makes September one of the most windless months of the year for Plymouth.

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 Plymouth in September is 6.3 hours.