World Resorts USA Block Island Weather

Block Island sea water temperature

Current sea water temperature:
+46.4°F
Minimum sea water temperature in December: 55.0°F
Maximum sea water temperature in December: 45.1°F
Average sea water temperature in December: 50.3°F

Sea water temperature for the last 10 days:

December 16 46.4°F December 11 49.3°F
December 15 48.0°F December 10 49.6°F
December 14 48.4°F December 9 49.3°F
December 13 47.7°F December 8 49.6°F
December 12 49.1°F December 7 49.8°F

When is the warmest sea in Block Island?

Based on the data about daily sea water temperature for the last three years the warmest sea in Block Island was noticed in August, July and September.

Monthly Sea Temperatures in Block Island, °F

Sea water temperature in August, °F

Show year:
2025
2024
2023

The average sea water temperature in August of 2025 was 69.0°F. The highest and lowest sea temperatures during the month were 71.1°F and 66.9°F.

Sea water temperature in July, °F

Show year:
2025
2024
2023

The average sea water temperature in July of 2025 was 68.5°F. The highest and lowest sea temperatures during the month were 71.6°F and 65.1°F.

Sea water temperature in September, °F

Show year:
2025
2024
2023

The average sea water temperature in September of 2025 was 68.0°F. The highest and lowest sea temperatures during the month were 68.9°F and 66.6°F.

Best time for vacation in Block Island

Sunniest months:
November 16 days
September 14 days
October 14 days
Warmest months:
July 74.4 °F
August 73.5 °F
September 68.8 °F
Warmest sea temp:
August 70.1 °F
July 68.6 °F
September 68.3 °F
Coldest months:
January 37.4 °F
February 37.4 °F
March 42.7 °F
Rainiest months:
October 4 days
January 3 days
March 3 days
Windiest months:
November 15.7 mph
January 15.6 mph
March 15.4 mph

Block Island on a weather map

Block Island
+30°F
E 18 mph
Feels like: +21°F
Precip.: 0%
Places in USA:
Name
°F
+25°F
+75°F
+75°F
+46°F
+54°F
+68°F
+72°F
+70°F
+23°F
+54°F
+46°F
+54°F
+52°F
+43°F
+18°F
24 Hours Forecast
Block Island
Local time: 09:08
December 16, tuesday
1200
36°F
E
11 mph
1500
37°F
E
12 mph
1800
39°F
E
13 mph
2100
37°F
NE
17 mph
December 17, wednesday
0000
39°F
NE
24 mph
0300
41°F
NE
26 mph
0600
43°F
NE
27 mph
0900
46°F
NE
27 mph
Units of measurement: °C / °F