Measurements:
°C
°F
Nantucket
80°F
NE 19 mph
Feels like: 82°F
Precip: 6%
World Resorts USA Nantucket Weather

Nantucket Sea Water Temperature

Current Sea Water Temperature:
+74.0°F
Maximum Sea Water Temperature in August: 82.0°F
Minimum Sea Water Temperature in August: 69.6°F
Average water temperature in August: 74.4°F

Sea Water Temperature for the Last 10 Days:

August 25 74.0°F August 20 74.8°F
August 24 74.4°F August 19 75.4°F
August 23 72.0°F August 18 74.4°F
August 22 72.4°F August 17 73.6°F
August 21 72.6°F August 16 74.6°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: 2026 2025 2024

The average sea surface temperature in August 2026 for Nantucket was 74.0°F. The maximum and minimum values were 69.6°F and 76.4°F respectively.

Sea Water Temperature in July

Select Year: 2026 2025 2024

The average sea surface temperature in July 2026 for Nantucket was 71.7°F. The maximum and minimum values were 68.6°F and 74.2°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:
June 14 days
September 13 days
October 13 days
The most warm months:
July 73.9 °F
August 73.3 °F
September 69.0 °F
Warmest sea temperature:
August 74.3 °F
July 72.3 °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
Boston +80
Chicago +80
Hawaii +84
Houston +106
Las Vegas +116
Los Angeles +96
Maui +70
Miami +92
Myrtle Beach +84
New York +82
San Diego +96
San Francisco +64
Santa Monica +86
Sarasota +92
Washington +84
24 Hours Weather Forecast
Nantucket
Local time: 17:45
25 aug, tuesday
1800 80°F
NE
19 mph
2100 72°F
E
19 mph
26 aug, wednesday
0000 70°F
E
14 mph
0300 72°F
E
14 mph
0600 72°F
E
12 mph
0900 70°F
SE
13 mph
1200 72°F
E
9 mph
1500 72°F
E
9 mph