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.
National forecast responsibility changes quickly across these coasts and straits. Check the exact marine zone, tropical-system alerts where applicable, visibility and the latest local port or traffic notices.
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
Check national coastal products and offshore warnings for the exact leg.
Vietnam’s long South China Sea coast cannot be represented by one city or one maritime forecast sector.
Use the national hydrometeorological service’s marine wind, wave and tropical warnings for the exact coast; check the arrival port and the offshore leg independently.
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.
Find the marine bulletin, not only the homepage
The national forecast centre's marine menu includes strong-wind, high-wave and thunderstorm bulletins. Select the dated item and actual named coastal or offshore region for the plotted route; a homepage link is not the product itself. The link here is an official entry menu, not a verified current bulletin displayed on this page. A translation should retain the original region name and issue time, with uncertainties marked rather than silently inferred.
- Vietnam national hydrometeorological forecast centre — Marine strong-wind/wave/thunderstorm bulletin menu; live fetch unavailable Direct product verification is limited; obtain the current issue from the issuer.
A long coast needs source and exposure hand-offs
A northern, central or southern coastal itinerary is not one forecast point. Separate headland exposure, open-water sections and destination approaches at their actual ETAs. Where the route continues into another service's waters, identify the next issuer through WMO–IMO. Compare swell direction and visibility separately from average wind, and do not treat a harbour observation as representative of the following offshore section.
- Vietnam national hydrometeorological forecast centre
- WMO–IMO marine warnings and issuer directory — METAREA service selection; website can have delayed or interrupted products
Make source completeness a prerequisite
Before comparing departure times, obtain a current official marine and tropical-system picture covering arrival as well as departure. If the exact live product or its translation is missing, state which part of the comparison remains unsupported. A shorter checked plan may be assessed separately, but the gap should not be filled with a confident model narrative. Port access, security and navigational restrictions are independent authoritative checks.
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.