Massachusetts boating conditions
Nantucket Sound marine forecast
A harbor-by-harbor view of the Nantucket Sound marine forecast across the Cape, Martha’s Vineyard, and Nantucket sides of the sound.
For the rest of today: Nantucket Sound SW 10–15 kt, gusts 20, seas 2–3 ft. Best day this week: Sun, Nov 8. Sun, Nov 8 is the mildest day in the forecast. It is still Nope on at least one period.
Forecast checked Thu, Nov 5, 2026, 3:03 AM EST · National Weather Service coastal waters forecast issued 1:03 AM EST · harbor briefings updated 3:03 AM EST · water temperature updated 2:54 AM EST
Right now
Nantucket Sound conditions today
Each flag is that harbor's live call. Zone labels use the coastal waters forecast for the rest of today.
- Nantucket SoundSSW 8 kt gust 10
NWS coastal waters forecast
Nantucket Sound forecast by zone
Each period is scored with the same limits as the harbor pages: 15 kt wind, 20 kt gusts, 2.5 ft seas. Thunderstorms or reduced visibility turn a period to Caution.
The sound between the Cape, Martha's Vineyard, and Nantucket
No advisoryOfficial NWS text for each zone
Nantucket Sound (ANZ232)
Rest Of Tonight: SW winds 10 to 15 kt. Seas around 2 ft. Wave Detail: SW 2 ft at 3 seconds and SE 1 foot at 9 seconds.
Thu: SW winds 10 to 15 kt with gusts up to 20 kt. Seas 2 to 3 ft. Wave Detail: SW 2 ft at 3 seconds and SE 1 foot at 9 seconds. Patchy fog in the morning with vsby 1 NM or less.
Thu Night: S winds 15 to 20 kt. Seas 2 to 3 ft. Wave Detail: SW 3 ft at 4 seconds and SE 1 foot at 9 seconds. A chance of rain after midnight.
Fri: S winds around 15 kt with gusts up to 20 kt. Seas 2 to 3 ft. Wave Detail: SW 3 ft at 4 seconds and SE 1 foot at 9 seconds. Patchy fog. Rain. Vsby 1 to 3 NM.
Fri Night: S winds 10 to 15 kt, diminishing to 5 to 10 kt after midnight. Seas 2 to 3 ft. Wave Detail: S 2 ft at 5 seconds and SE 1 foot at 9 seconds. Patchy fog. Rain. Vsby 1 to 3 NM.
Sat: S winds 5 to 10 kt, becoming W 10 to 15 kt in the afternoon. Seas 2 to 3 ft. Wave Detail: SW 2 ft at 6 seconds and SE 1 foot at 9 seconds. Rain, mainly in the morning. Patchy fog in the morning with vsby 1 to 3 NM.
Sat Night: W winds 10 to 15 kt, increasing to 20 to 25 kt after midnight. Seas 3 to 5 ft. A chance of rain after midnight.
Sun: W winds 20 to 25 kt. Seas 3 to 5 ft. A chance of rain.
Sun Night through Mon Night: NW winds 20 to 25 kt. Seas 2 to 4 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height.
Five-day trend
Wind and seas across Nantucket Sound
Day and night bars for each zone, in the same wind and seas chart style as a harbor page. A missing bar is a period the forecast did not quantify.
Nantucket Sound
Dashed limit on the harbor pages: 15 kt. Bars are the top of the forecast range.
Dashed limit on the harbor pages: 2.5 ft. Bars are the top of the forecast range.
Harbor-level briefings
Compare conditions around Nantucket Sound
Cape Cod shore
Harbors along the north and east sides of Nantucket Sound.
A central Cape Cod harbor in Lewis Bay with ferry traffic and ready access to Nantucket Sound.
8 ktseas 2 ft56°F water
Conditions are Caution now, then improve to Go around 4 AM.
A tidal South Cape river and harbor opening onto Nantucket Sound, with a marked entrance and extensive protected water inland.
8 ktseas 2 ft56°F water
Conditions are Caution now, then improve to Go around 4 AM.
An outer Cape destination with shifting bars, strong currents, and access to both Chatham and Stage harbors.
8 ktseas 2 ft56°F water
Conditions are Caution now, then improve to Go around 4 AM.
Island harbors
Martha’s Vineyard and Nantucket departure points.
A major cruising island with distinct harbors at Vineyard Haven, Edgartown, Oak Bluffs, and Menemsha.
8 ktseas 2 ft56°F water
Conditions are Caution now, then improve to Go around 4 AM.
A compact seasonal harbor on the northeast shore of Martha's Vineyard with ferry traffic and a closely marked entrance.
8 ktseas 2 ft56°F water
Conditions are Caution now, then improve to Go around 4 AM.
A protected Martha's Vineyard harbor extending into Katama Bay, with strong tidal flow, dense moorings, and an active ferry crossing.
8 ktseas 2 ft56°F water
Conditions are Caution now, then improve to Go around 4 AM.
An offshore island destination with a well-marked but busy harbor entrance and exposed surrounding waters.
8 ktseas 2 ft56°F water
Conditions are Caution now, then improve to Go around 4 AM.
Tide charts
Tide charts around Nantucket Sound
- High tide 4:34 AM · 2.13 ft · Low tide 12:31 PM · 0.2 ft · High tide 4:58 PM · 1.8 ft57.2°Fwater
- Low tide 2:48 AM · -0.13 ft · High tide 8:41 AM · 5.29 ft · Low tide 3:15 PM · -0.08 ft · High tide 9:07 PM · 5.16 ft—water unavailable
- Low tide 1:15 AM · 0.14 ft · High tide 8:20 AM · 2.68 ft · Low tide 1:50 PM · 0.14 ft · High tide 8:48 PM · 2.34 ft—water unavailable
- Low tide 2:08 AM · 0.26 ft · High tide 8:55 AM · 3.51 ft · Low tide 2:46 PM · 0.27 ft · High tide 9:23 PM · 3.24 ft56.5°Fwater
The regional picture
One body of water. More than one kind of boat day.
The official Nantucket Sound marine forecast is the National Weather Service coastal waters forecast from the Boston/Norton office, which covers the sound as its own zone (ANZ232) beside neighboring Vineyard Sound (ANZ233). The NWS issues it about four times a day and updates it when conditions change; the harbor briefings below refresh with the latest available forecast and observation data through the day.
Nantucket Sound sits between three very different shorelines, with shoals, island passages, and a lot of room for a breeze to make the trip home less charming than the trip out. A single forecast headline is useful; the local departure and destination context is better.
Use the groups below to compare Cape-side harbors with Martha’s Vineyard and Nantucket. Each briefing shows the sources and timing behind its call, including when important data is incomplete.
Before leaving the dock
Three useful checks for Nantucket Sound
- Compare both ends of an island crossing rather than checking only the departure harbor.
- Read wave period and wind direction with wave height; the same number can feel very different underway.
- Allow for shoals, passages, and local current effects that a broad sound forecast cannot describe.
What this regional guide can - and cannot - do
These pages make it easier to compare the latest available forecast and observation inputs around Nantucket Sound. They are planning aids, not navigation or safety guarantees. Check the official coastal waters forecast, current observations and notices, local conditions, and your own boat and crew before departure.
See how Boat or Nope builds each call