Block Island, RI to Onset Harbor, MA map preview
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Block Island, RI to Onset Harbor, MA Marine Weather Route Forecast

Open-water trip, this route passes near the Elizabeth Islands and crosses Buzzards Bay. It requires careful weather routing, as conditions can change rapidly.

Latest Automated Forecast

Optimized for marine passage planning, vessel routing, and coastal or offshore weather tracking. This automated marine weather routing tool updates daily using premium data models. Below is the weather, wave, and ocean current layout for a standard vessel transit from Block Island, RI to Onset Harbor, MA.

Generated: 2026-09-04T10:39:18.852663+00:00 • Distance: 58.1 NM • Departure: 2026-09-04T08:00:00-04:00 • Speed: 6 knots
Time Wind Waves Ocean Current Air/Water
2026-09-04T12:00:00+00:00 7.8293765 kts 0.7 m 0.5 kts SE SE 22.1 / 21.3 °C
2026-09-04T16:00:00+00:00 8.2613421 kts 0.64 m 0.2 kts E E 24.7 / 22.0 °C
Locked forecast rows are available to signed-in users.

Route Passage Summary & Sea State

Expect a majority of reaching conditions with steady motion. Winds range from 0 to 8 kts with waves 1.0 to 2.3 ft with period of 4 to 7 seconds. Overall, seas and wind frequently opposed, expect confused motion. Wind angles: 100% reaching. Sea state: 25% cross-seas, 75% opposed.

More Detail

Points of Sail

CategoryPoint of SailWind AnglePortion of Passage
On the NoseNo-Go Zone0–45°0%
ReachingClose Hauled45–80°25%
ReachingBeam Reach80–110°25%
ReachingBroad Reach110–145°50%
FollowingRun145–180°0%

Sea State & Wave Motion

Sea StateWind vs. WavesBoat MotionPortion of Passage
AlignedWaves run with the windSteady, organized0%
Cross SeasWaves cross the windRolling25%
OpposedWaves against the windChoppy, confused75%
Historical Forecasts Download GPX File

Related Routes

Onset Harbor, MA to Block Island, RI
58.6 NM 22 waypoints
Block Island, RI to Cuttyhunk, MA
37 NM 7 waypoints
Block Island, RI to Nantucket, MA
69.8 NM 11 waypoints
Block Island, RI to Atlantic Highlands / Sandy Hook, NJ
130 NM 10 waypoints

Navigation Responsibility

This forecast is for informational purposes only. You are responsible for your own navigation and safety at sea. Always verify weather conditions with official sources, maintain a proper watch, and exercise prudent seamanship. Do not rely solely on this forecast for critical navigation decisions. See our Terms of Service for full details.