Measurements:
°C
°F
Nantucket
86°F
E 22 mph
Feels like: 94°F
Precip: 7%
World Resorts USA Nantucket Weather

Nantucket Sea Water Temperature

Current Sea Water Temperature:
+71.0°F
Maximum Sea Water Temperature in July: 78.4°F
Minimum Sea Water Temperature in July: 65.4°F
Average water temperature in July: 72.3°F

Sea Water Temperature for the Last 10 Days:

July 15 71.0°F July 10 70.0°F
July 14 70.6°F July 09 71.4°F
July 13 71.6°F July 08 71.8°F
July 12 72.2°F July 07 72.8°F
July 11 69.2°F July 06 73.6°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: 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: 2026 2025 2024

The average sea surface temperature in July 2026 for Nantucket was 71.3°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
October 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
Boston +94
Chicago +88
Hawaii +80
Houston +90
Las Vegas +120
Los Angeles +106
Maui +76
Miami +100
Myrtle Beach +96
New York +114
San Diego +96
San Francisco +76
Santa Monica +84
Sarasota +102
Tampa +100
24 Hours Weather Forecast
Nantucket
Local time: 14:18
15 jul, wednesday
1500 86°F
E
22 mph
1800 82°F
SE
8 mph
2100 78°F
S
9 mph
16 jul, thursday
0000 74°F
S
4 mph
0300 78°F
NE
9 mph
0600 78°F
NE
12 mph
0900 76°F
NE
16 mph
1200 76°F
NE
16 mph