Marine Weather API for the Northeast USA

Marine Weather Challenges in the Northeast

The Northeast coast stretches from the Jersey Shore through New York Harbor, Long Island Sound, Block Island Sound, Narragansett Bay, Buzzards Bay, and up through Cape Cod to the Gulf of Maine. This vast stretch of coastline encompasses some of the most diverse and demanding marine environments on the Atlantic seaboard.

This region has the highest concentration of recreational sailors in the country — Newport, Rhode Island is the sailing capital of America, home to America's Cup history and dozens of major regattas throughout the season.

New Jersey's shore and New York's waters support massive fishing fleets — from the canyons 60+ miles offshore to nearshore striped bass and bluefish runs that draw thousands of boats every spring and fall.

Connecticut's Long Island Sound is one of the most sailed bodies of water in America, with conditions that can change rapidly as weather funnels through the east-west corridor between Connecticut and Long Island.

Winter brings intense nor'easters that can halt all marine activity for days. Spring and fall offer beautiful sailing but with rapidly changing conditions. Summer brings fog that can reduce visibility to near zero, especially from Connecticut through Maine.

Get a Marine Forecast for the Northeast

Here's how to get an AI-powered marine weather forecast for Newport, Rhode Island — Narragansett Bay, the sailing capital of America:

curl -X POST https://api.sealegs.ai/v3/spotcast \
  -H "X-API-Key: your_api_key" \
  -d '{
    "latitude": 41.4901,
    "longitude": -71.3128,
    "start_date": "2026-07-12",
    "num_days": 3,
    "vessel_info": {
      "type": "sailing",
      "length_ft": 38
    }
  }'

{
  "summary": "Good three-day window for a 38ft sailing vessel
    off Newport, RI. Southwest winds 12-16kt building to 18kt
    in the afternoon — typical summer sea breeze pattern. Seas
    2-4ft in Narragansett Bay, building to 4-6ft in Block Island
    Sound. Good sailing conditions with a reminder that fog may
    develop after sunset as warm air moves over cooler waters.
    Confidence high for next 48 hours.",
  "daily_forecasts": [
    {
      "date": "2026-07-12",
      "classification": "Good",
      "confidence": 0.91,
      "wind_speed_kt": 14,
      "wind_gust_kt": 18,
      "wave_height_ft": 3.2,
      "wave_period_s": 5
    }
  ]
}

The same request works for any Northeast coordinates. Use 40.4640, -73.9862 for Sandy Hook, NJ, 41.0714, -71.8571 for Montauk, NY, 41.3557, -72.0995 for New London, CT, or 41.1726, -71.5775 for Block Island, RI.

Key Weather Parameters for the Northeast

The API returns a full set of marine weather parameters. For Northeast waters, these are especially important:

• Wind speed & direction — Southwest sea breezes dominate in summer while northwest gales prevail in winter; direction determines which harbors offer protection
• Wave height & period — Short-period chop in Long Island Sound vs long-period Atlantic swell off Montauk and Block Island — a critical distinction for vessel safety and comfort
• Visibility — Fog forecasts are essential for navigating crowded Northeast waters with heavy commercial traffic
• Gusts — Sea breeze fronts and thunderstorm outflows create sudden gusts that matter for racing and daysailing
• Tidal data — Strong currents at The Race (eastern Long Island Sound), Hell Gate, and Block Island Sound affect all vessel operations

Use Cases in the Northeast

Popular Northeast Coordinates

Here are commonly used coordinates for Northeast marine forecasts:

• Sandy Hook, NJ — 40.4640, -73.9862
• Montauk, NY — 41.0714, -71.8571
• Oyster Bay, NY (Long Island Sound) — 40.8710, -73.5318
• New London, CT — 41.3557, -72.0995
• Mystic, CT — 41.3543, -71.9662
• Newport, RI — 41.4901, -71.3128
• Block Island, RI — 41.1726, -71.5775
• Nantucket, MA — 41.2835, -70.0995
• Portland, ME — 43.6591, -70.2568