Measurements:
°C
°F
Charlestown
62°F
SW 14 mph
Feels like: 62°F
Precip: 5%
World Resorts USA Charlestown Weather

Charlestown Sea Water Temperature

Current Sea Water Temperature:
+70.8°F
Maximum Sea Water Temperature in September: 76.2°F
Minimum Sea Water Temperature in September: 65.2°F
Average water temperature in September: 70.6°F

Sea Water Temperature for the Last 10 Days:

September 15 70.8°F September 10 71.0°F
September 14 71.2°F September 09 70.8°F
September 13 70.8°F September 08 71.4°F
September 12 71.2°F September 07 71.6°F
September 11 71.8°F September 06 71.6°F

When is the Warmest Sea for Charlestown?

According to our data for the last three years for Charlestown the highest average sea water temperature was in August, July and September.

Average Water Temperature by Month, °F

Sea Water Temperature in August

Select Year: 2026 2025 2024

The average sea surface temperature in August 2026 for Charlestown was 72.9°F. The maximum and minimum values were 71.6°F and 75.2°F respectively.

Sea Water Temperature in July

Select Year: 2026 2025 2024

The average sea surface temperature in July 2026 for Charlestown was 70.6°F. The maximum and minimum values were 68.2°F and 72.6°F respectively.

Sea Water Temperature in September

Select Year: 2026 2025 2024

The average sea surface temperature in September 2026 for Charlestown was 71.5°F. The maximum and minimum values were 70.8°F and 72.6°F respectively.

Best Time to Visit Charlestown
The most sunny months:
November 17 days
September 14 days
October 14 days
The most warm months:
July 78.9 °F
August 77.8 °F
September 72.1 °F
Warmest sea temperature:
August 73.1 °F
July 71.6 °F
September 70.6 °F
The most cold months:
January 35.0 °F
February 35.5 °F
December 41.0 °F
The most rainy months:
October 4 days
November 3 days
January 2 days
The most windy months:
January 13 mph
December 13 mph
March 12 mph

Charlestown on the Weather Map

USA Resorts:
NAME
Boston +62
Chicago +66
Hawaii +80
Las Vegas +80
Los Angeles +72
Maui +66
Miami +88
Myrtle Beach +78
New York +66
Panama City Beach +90
San Diego +70
San Francisco +60
Santa Monica +72
Sarasota +86
Washington +66
24 Hours Weather Forecast
Charlestown
Local time: 09:42
15 sep, tuesday
1200 66°F
W
9 mph
1500 66°F
NW
7 mph
1800 66°F
NW
6 mph
2100 64°F
NW
7 mph
16 sep, wednesday
0000 64°F
NW
7 mph
0300 62°F
NE
2 mph
0600 62°F
N
3 mph
0900 66°F
NE
6 mph