An Aegean island passage may begin behind a sheltered coast, cross an exposed channel and arrive in a different marine-forecast sector. Use this page as a source and decision checklist, not as a live forecast or an assessment that your route is safe. Match every leg to the named areas in the current bulletin.
Open the right source first
1. Official warnings
HNMS warnings and the warnings in its marine bulletin. Check the affected sea area and valid time before looking at a coloured map.
2. Official sea-area forecast
HNMS marine forecast. Follow every named Aegean sector crossed by your route; note issue time, wind direction and force, sea state and trend.
3. Turkish coast, when relevant
For a leg near Turkey, add the MGM 24-hour marine forecast. Do not stretch a Greek sector forecast across waters served by another national service.
4. Observations and model context
HCMR POSEIDON offers buoy observations and marine model products. Check station location and timestamp: one buoy or shore station cannot describe every island gap.
Turn an area forecast into a passage check
- Draw the whole leg: departure, exposed straits, headlands, intended arrival and realistic diversions. Locate each in the HNMS named forecast areas, rather than using the nearest city forecast.
- Read time as carefully as wind: distinguish issue time from valid period, convert the time zone deliberately, and estimate when your yacht could reach each exposed point at a range of realistic speeds.
- Compare wind with sea: check direction, gusts, wave and swell information, visibility and thunderstorms. Local acceleration, lee effects and harbour-entrance exposure depend on the exact route and may be smoothed in a model grid.
- Check what is happening: compare recent observations with the forecast, allowing for location and exposure. A mismatch calls for a fresh bulletin and more caution, not an automatic verdict that the forecast is wrong.
- Preserve options: record a postponement or diversion point, the next forecast update and a second way to receive warnings after mobile coverage ends.
Explore the model map — optional
Windy is a third-party visual model display, not the issuer of Greek marine warnings. The map below is not fetched until you choose a layer; its centre is the Aegean, not your route. Verify model run and valid hour in Windy, then return to the current official bulletin.
The map loads only after a click and then connects to Windy. Without JavaScript, open Windy directly.
If connectivity is limited
Before departure, save or write down the latest bulletin, its issue and valid times and the next scheduled check. Identify a working second channel for current warnings, such as an appropriate coastal radio or MGM marine broadcast information when sailing near Turkey. A downloaded map is a snapshot, not a replacement for new warnings.
For the method behind this checklist, read how to read a marine forecast and wind and waves. The weather-tools guide explains when to use maps, routing apps and low-bandwidth software.
Scope and review: source links checked 24 September 2026. This page contains no current conditions, personalised routing or universal departure threshold. AI-assisted and expert passage briefings are being developed, not offered here yet. Always check the live sources and local notices; the skipper makes the decision.