Maryland, USA
Long-term weather forecast
Long-term weather forecast

December weather forecast and climate
Charlestown, MD

Ocean temperature

In December, the average ocean temperature in Charlestown, Maryland, is 48.6°F (9.2°C).
Note: Swimming in 48.6°F (9.2°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.


With an average of 9.4h of daylight, December has the shortest days of the year in Charlestown, Maryland.

What is the ocean temperature in December in Charlestown?

In Charlestown, the average seawater temperature in December is 48.6°F (9.2°C). At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.

What is the month with the shortest days in Charlestown?

The month with the shortest days is December, with an average of 9.4h of daylight.

How many hours of daylight does Charlestown have in December?

The average length of the day in December in Charlestown, Maryland, is 9.4h.
Average sea temperature in December - Charlestown, MD
  • Average sea temperature in December: 48.5°F

The best month for swimming (with the highest average sea temperature) is August (76.3°F).
The coldest month (with the lowest average sea temperature) is February (40.9°F).

Average daylight in December - Charlestown, MD
  • Average daylight in December: 9.4h

The month with the longest days is June (Average daylight: 14.9h).
The month with shortest days is December (Average daylight: 9.4h).