This is a pre-passage source and decision desk, not a current forecast or clearance to depart. The map is centred approximately on the area, not on your route or a forecast-zone boundary.
Check the current tropical warning separately from the routine marine forecast; neither an island app nor a model animation substitutes for the responsible coastal bulletin. Reef entrances also require current chart and local-authority information.
1. Primary sources
Open current bulletins and warnings for every sea area on the route. These links are starting points, not a promise that each covers the whole location; if unsure, identify the issuer through WMO–IMO.
2. Route and local effects
NWS San Juan coastal zones and channel exposure matter more than one town forecast.
A Puerto Rico–Spanish Virgin Islands trip may cross different NWS San Juan coastal zones despite its modest distance.
Choose each named NWS zone, check channel exposure and the separate tropical outlook; a forecast for San Juan city is not a passage forecast.
How to use this source set
Start with the warning, then the marine text for the exact named area. If the route crosses a zone boundary, obtain both bulletins. Note issue and valid times, wind units and the meaning of wave height. Where a link opens an agency portal, navigate to its current marine product; a homepage is not itself a forecast.
Compare with an exposed station or buoy if available. Check its position and observation time: a sheltered station does not overturn a warning for an open channel. If a bulletin is missing or stale, identify the issuing service via WMO–IMO and defer the decision until current information is available.
Before-passage check
- Mark departure, exposed legs, arrival and feasible diversions; find the responsible named marine areas for each.
- Check warnings, issue and valid times; assess conditions when you expect to reach each leg, not only at departure.
- Compare wind and gusts, waves and swell, visibility, thunderstorms and local effects; do not infer a strait from a sheltered harbour.
- Compare recent observations where available, noting their time and exposure; a mismatch calls for another check.
- Set the next bulletin check, a reassessment trigger, an alternative and a backup communication channel.
Model map — optional
Windy is a third-party model display, not the issuer of official warnings. Choose a layer and check its valid hour and model run. Nothing loads until you click.
Without JavaScript, open the map separately.
If connectivity fails
Before departure, save the current official text bulletin and warning with issue time. Arrange another way to receive updates, such as an appropriate coastal broadcast, NAVTEX or satellite channel. A saved map cannot replace new warnings.
How to choose weather tools · All sailing areas
Scope: Source list assembled 25 September 2026; check its freshness and coverage before use. This public area guide is not a current personalised forecast, navigational notice service or safety verdict. Personalised forecasts with AI and experts are in closed testing; public booking is not open. The skipper makes the decision.
Culebra and Vieques are named marine waters, not a San Juan icon
Use the San Juan zone directory to trace the actual waters east of Puerto Rico, around Vieques and near Culebra. These are useful search descriptions; do not select a zone only because it contains the island name. Compare the complete track with the current boundary map and include any adjoining zone. Add the applicable Marine Weather Message and short-term marine warning, not merely the coastal synopsis.
- NWS San Juan zone products — Puerto Rico, USVI and geographically defined neighbouring waters; read each boundary.
Exposure changes at an island's end
On a Fajardo–Culebra or Vieques plan, distinguish the departure coast, open crossing and final approach. Compare the forecast hour at each rather than treating the island hop as instantaneous. Select a measurement with relevant exposure, keeping sheltered wind and offshore sea observations separate. A beach surf or rip-current product can add shore context but is not a vessel sea-state forecast for the crossing.
Plan the return before extending the outward leg
For a same-day trip, test a delayed return with the destination warning still visible. A later, smoother outward window may move the return into stronger wind, squalls or reduced visibility. If the revised timing exceeds the crew's comfort constraints or loses the intended arrival light, shorten the island plan while the practical alternative remains available. Do not seek a reassuring city forecast to overrule the marine product.
- NWS San Juan zone products
- NHC marine products — Broader Gulf, Caribbean and tropical Atlantic/Pacific context; confirm the current product at the issuer. Direct product verification is limited; obtain the current issue from the issuer.
Editorial review of this material: 27 September 2026. This date concerns the page content; check current forecast issue times and validity at the original sources.
- United States
Choose a bay, coastal, offshore, Great Lakes or ocean product for the actual track.