Measurements:
°C
°F
Block Island
20°F
E 17 mph
Feels like: 6°F
Precip: 0%
World Resorts USA Block Island Weather

Block Island Sea Water Temperature

Current Sea Water Temperature:
+38.2°F
Maximum Sea Water Temperature in January: 49.4°F
Minimum Sea Water Temperature in January: 38.2°F
Average water temperature in January: 43.5°F

Sea Water Temperature for the Last 10 Days:

January 29 38.2°F January 24 39.4°F
January 28 39.2°F January 23 39.8°F
January 27 39.0°F January 22 40.2°F
January 26 39.2°F January 21 39.8°F
January 25 39.4°F January 20 40.4°F

When is the Warmest Sea for Block Island?

According to our data for the last three years for Block Island 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: 2025 2024 2023

The average sea surface temperature in August 2025 for Block Island was 71.1°F. The maximum and minimum values were 68.8°F and 73.4°F respectively.

Sea Water Temperature in July

Select Year: 2025 2024 2023

The average sea surface temperature in July 2025 for Block Island was 70.5°F. The maximum and minimum values were 66.8°F and 74.0°F respectively.

Sea Water Temperature in September

Select Year: 2025 2024 2023

The average sea surface temperature in September 2025 for Block Island was 70.0°F. The maximum and minimum values were 68.4°F and 71.0°F respectively.

Best Time to Visit Block Island
The most sunny months:
November 16 days
December 14 days
September 14 days
The most warm months:
July 77.2 °F
August 76.1 °F
September 70.9 °F
Warmest sea temperature:
August 72.3 °F
July 70.7 °F
September 70.3 °F
The most cold months:
January 35.6 °F
February 36.1 °F
December 41.7 °F
The most rainy months:
October 4 days
January 3 days
March 3 days
The most windy months:
December 16 mph
January 16 mph
November 16 mph

Block Island on the Weather Map

USA Resorts:
NAME
Chicago 0
Hawaii +74
Honolulu +74
Houston +38
Las Vegas +48
Los Angeles +56
Maui +68
Miami +64
Miami Beach +70
New York +12
San Diego +60
San Francisco +50
Sarasota +58
Tampa +58
Washington +12
24 Hours Weather Forecast
Block Island
Local time: 10:54
29 jan, thursday
1200 20°F
E
17 mph
1500 20°F
SE
21 mph
1800 24°F
SE
22 mph
2100 22°F
SE
21 mph
30 jan, friday
0000 20°F
SE
22 mph
0300 18°F
SE
24 mph
0600 16°F
SE
25 mph
0900 16°F
E
25 mph