Measurements:
°C
°F
Nantucket
18°F
SE 22 mph
Feels like: 4°F
Precip: 0%
World Resorts USA Nantucket Weather

Nantucket Sea Water Temperature

Current Sea Water Temperature:
+46.8°F
Maximum Sea Water Temperature in December: 50.8°F
Minimum Sea Water Temperature in December: 37.6°F
Average water temperature in December: 44.6°F

Sea Water Temperature for the Last 10 Days:

December 04 46.8°F November 29 46.8°F
December 03 46.6°F November 28 46.8°F
December 02 46.6°F November 27 47.4°F
December 01 48.0°F November 26 47.0°F
November 30 46.8°F November 25 47.2°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:
June 13 days
September 13 days
October 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 35.5 °F
March 39.3 °F
The most rainy months:
January 4 days
October 4 days
December 3 days
The most windy months:
March 19 mph
January 19 mph
November 18 mph

Nantucket on the Weather Map

USA Resorts:
NAME
Chicago 0
Hawaii +78
Honolulu +78
Houston +46
Las Vegas +40
Los Angeles +52
Maui +72
Miami +72
Miami Beach +80
New York +18
San Diego +54
San Francisco +46
Sarasota +62
Tampa +62
Washington +28
24 Hours Weather Forecast
Nantucket
Local time: 02:18
05 dec, friday
0300 18°F
SE
22 mph
0600 18°F
S
16 mph
0900 22°F
S
6 mph
1200 26°F
NE
4 mph
1500 28°F
NE
9 mph
1800 30°F
NE
8 mph
2100 32°F
N
7 mph
06 dec, saturday
0000 34°F
N
6 mph