Measurements:
°C
°F
Nantucket
20°F
SE 18 mph
Feels like: 8°F
Precip: 0%
World Resorts USA Nantucket Weather

Nantucket Sea Water Temperature

Current Sea Water Temperature:
+34.4°F
Maximum Sea Water Temperature in January: 44.8°F
Minimum Sea Water Temperature in January: 32.0°F
Average water temperature in January: 38.9°F

Sea Water Temperature for the Last 10 Days:

January 29 34.4°F January 24 33.8°F
January 28 34.0°F January 23 36.0°F
January 27 35.2°F January 22 36.2°F
January 26 34.8°F January 21 34.0°F
January 25 34.8°F January 20 35.4°F

When is the Warmest Sea for Nantucket?

According to our data for the last three years for Nantucket 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 Nantucket was 71.9°F. The maximum and minimum values were 69.6°F and 75.8°F respectively.

Sea Water Temperature in July

Select Year: 2025 2024 2023

The average sea surface temperature in July 2025 for Nantucket was 70.7°F. The maximum and minimum values were 65.4°F and 75.4°F respectively.

Sea Water Temperature in September

Select Year: 2025 2024 2023

The average sea surface temperature in September 2025 for Nantucket was 69.7°F. The maximum and minimum values were 68.2°F and 71.6°F respectively.

Best Time to Visit Nantucket
The most sunny months:
October 13 days
September 13 days
June 13 days
The most warm months:
August 73.3 °F
July 72.9 °F
September 69.0 °F
Warmest sea temperature:
August 74.4 °F
July 72.4 °F
September 70.6 °F
The most cold months:
February 35.0 °F
January 35.2 °F
March 39.3 °F
The most rainy months:
October 4 days
January 3 days
December 3 days
The most windy months:
March 19 mph
January 19 mph
December 19 mph

Nantucket 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
Nantucket
Local time: 10:54
29 jan, thursday
1200 20°F
SE
18 mph
1500 20°F
SE
21 mph
1800 22°F
SE
25 mph
2100 22°F
SE
27 mph
30 jan, friday
0000 20°F
SE
29 mph
0300 18°F
E
28 mph
0600 16°F
E
27 mph
0900 16°F
E
28 mph