World Resorts USA Nantucket Weather

Nantucket sea water temperature

Current sea water temperature:
+39.6°F
Minimum sea water temperature in December: 50.7°F
Maximum sea water temperature in December: 38.8°F
Average sea water temperature in December: 44.7°F

Sea water temperature for the last 10 days:

December 30 39.6°F December 25 39.9°F
December 29 39.2°F December 24 40.8°F
December 28 39.2°F December 23 41.0°F
December 27 39.7°F December 22 42.3°F
December 26 39.7°F December 21 41.4°F

When is the warmest sea in Nantucket?

Based on the data about daily sea water temperature for the last three years the warmest sea in Nantucket was noticed in August, July and September.

Monthly Sea Temperatures in Nantucket, °F

Sea water temperature in August, °F

Show year:
2025
2024
2023

The average sea water temperature in August of 2025 was 69.7°F. The highest and lowest sea temperatures during the month were 73.2°F and 67.6°F.

Sea water temperature in July, °F

Show year:
2025
2024
2023

The average sea water temperature in July of 2025 was 68.7°F. The highest and lowest sea temperatures during the month were 72.9°F and 63.9°F.

Sea water temperature in September, °F

Show year:
2025
2024
2023

The average sea water temperature in September of 2025 was 67.7°F. The highest and lowest sea temperatures during the month were 69.4°F and 66.4°F.

Best time for vacation in Nantucket

Sunniest months:
June 13 days
September 13 days
October 13 days
Warmest months:
August 70.9 °F
July 70.6 °F
September 67.1 °F
Warmest sea temp:
August 72.0 °F
July 70.1 °F
September 68.5 °F
Coldest months:
February 36.5 °F
January 36.9 °F
March 40.4 °F
Rainiest months:
January 4 days
October 4 days
December 3 days
Windiest months:
March 19.1 mph
January 19.0 mph
December 18.9 mph

Nantucket on a weather map

Nantucket
+28°F
E 38 mph
Feels like: +14°F
Precip.: 0%
Places in USA:
Name
°F
+30°F
+75°F
+75°F
+66°F
+70°F
+70°F
+70°F
+70°F
+30°F
+79°F
+52°F
+59°F
+57°F
+55°F
+25°F
24 Hours Forecast
Nantucket
Local time: 17:52
December 30, tuesday
1800
28°F
E
38 mph
2100
30°F
E
38 mph
December 31, wednesday
0000
30°F
E
34 mph
0300
32°F
E
31 mph
0600
32°F
E
27 mph
0900
32°F
E
25 mph
1200
32°F
E
21 mph
1500
34°F
E
25 mph
Units of measurement: °C / °F