Measurements:
°C
°F
Nantucket
40°F
NW 14 mph
Feels like: 34°F
Precip: 100%
World Resorts USA Nantucket Weather

Nantucket Sea Water Temperature

Current Sea Water Temperature:
+40.4°F
Maximum Sea Water Temperature in April: 50.8°F
Minimum Sea Water Temperature in April: 39.6°F
Average water temperature in April: 45.4°F

Sea Water Temperature for the Last 10 Days:

April 03 40.4°F March 29 40.8°F
April 02 40.2°F March 28 40.0°F
April 01 39.6°F March 27 40.2°F
March 31 43.0°F March 26 40.6°F
March 30 41.0°F March 25 40.8°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
June 13 days
September 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 34.6 °F
January 34.9 °F
March 39.7 °F
The most rainy months:
October 4 days
January 3 days
December 3 days
The most windy months:
January 19 mph
March 19 mph
December 19 mph

Nantucket on the Weather Map

USA Resorts:
NAME
Chicago +46
Hawaii +74
Honolulu +74
Houston +74
Las Vegas +54
Los Angeles +56
Maui +66
Miami +74
Miami Beach +78
New York +40
San Diego +58
San Francisco +50
Sarasota +72
Tampa +72
Washington +48
24 Hours Weather Forecast
Nantucket
Local time: 05:47
03 apr, friday
0600 40°F
NW
14 mph
0900 42°F
N
12 mph
1200 46°F
NE
12 mph
1500 46°F
NE
22 mph
1800 46°F
NE
27 mph
2100 46°F
NE
26 mph
04 apr, saturday
0000 46°F
NE
27 mph
0300 46°F
NE
27 mph