Measurements:
°C
°F
Charlestown
58°F
SE 17 mph
Feels like: 54°F
Precip: 2%
World Resorts USA Charlestown Weather

Charlestown Sea Water Temperature

Current Sea Water Temperature:
+65.8°F
Maximum Sea Water Temperature in October: 70.4°F
Minimum Sea Water Temperature in October: 61.0°F
Average water temperature in October: 64.9°F

Sea Water Temperature for the Last 10 Days:

October 05 65.8°F September 30 63.6°F
October 04 66.4°F September 29 66.6°F
October 03 65.4°F September 28 67.0°F
October 02 66.4°F September 27 67.4°F
October 01 65.8°F September 26 67.6°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 70.2°F. The maximum and minimum values were 63.6°F and 72.6°F respectively.

Best Time to Visit Charlestown
The most sunny months:
November 17 days
October 14 days
December 13 days
The most warm months:
July 78.9 °F
August 77.8 °F
September 71.8 °F
Warmest sea temperature:
August 73.1 °F
July 71.6 °F
September 70.5 °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
F°
Boston +58
Chicago +62
Hawaii +82
Houston +86
Las Vegas +92
Los Angeles +100
Maui +74
Miami +88
Myrtle Beach +70
New York +62
San Diego +84
San Francisco +66
Santa Monica +94
Sarasota +84
Washington +64
24 Hours Weather Forecast
Charlestown
Local time: 20:27
05 oct, monday
2100 58°F
SE
17 mph
06 oct, tuesday
0000 54°F
SE
19 mph
0300 52°F
SE
16 mph
0600 48°F
SE
20 mph
0900 48°F
SE
17 mph
1200 56°F
SE
15 mph
1500 60°F
SE
16 mph
1800 58°F
SE
14 mph