The highest day temperature in December 2025 was 59°F. The lowest night temperature was 9°F. The average values for day and night temperatures during December were 34.8°F и 25.7°F respectivly.

The average sea surface temperature in December 2025 for Plymouth was 42.1°F. The maximum and minimum values were 39.0°F and 46.0°F respectively.

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

Precipitation total in December for Plymouth is 1.3 in. It makes december one of the most rainy months of the year.

The average wind speed in December is 10.5 mph. It makes December one of the most windy 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 December is 5.0 hours.