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.
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.
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.
Open marine conditions MABass RiverA tidal South Cape river and harbor opening onto Nantucket Sound, with a marked entrance and extensive protected water inland.
Open marine conditions MAChathamAn outer Cape destination with shifting bars, strong currents, and access to both Chatham and Stage harbors.
Open marine conditionsIsland harbors
Martha’s Vineyard and Nantucket departure points.
A major cruising island with distinct harbors at Vineyard Haven, Edgartown, Oak Bluffs, and Menemsha.
Open marine conditions MAOak Bluffs HarborA compact seasonal harbor on the northeast shore of Martha's Vineyard with ferry traffic and a closely marked entrance.
Open marine conditions MAEdgartown HarborA protected Martha's Vineyard harbor extending into Katama Bay, with strong tidal flow, dense moorings, and an active ferry crossing.
Open marine conditions MANantucket HarborAn offshore island destination with a well-marked but busy harbor entrance and exposed surrounding waters.
Open marine conditionsTide charts
Tide charts around Nantucket Sound
- Woods Hole tide chartCO-OPS 8447930
- Chatham tide chartCO-OPS 8447435
- Edgartown Harbor tide chartCO-OPS 8448558
- Nantucket Harbor tide chartCO-OPS 8449130
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