The highest day temperature in December 2025 was 51°F. The lowest night temperature was 3°F. The average values for day and night temperatures during December were 29.3°F и 22.8°F respectivly.

The average sea surface temperature in December 2025 for Rockland was 42.2°F. The maximum and minimum values were 37.4°F and 46.6°F respectively.

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

Precipitation total in December for Rockland is 1.4 in. It makes december the most rainy month of the year.

The average wind speed in December is 12.3 mph. It makes December the most windy month of the year for Rockland.

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 Rockland in December is 4.7 hours.