How to choose a marine weather app for coastal sailing

Choose a marine weather app that lets you check the places and conditions that matter along your trip, and that explains where its forecasts and alerts come from. A handsome wind chart is helpful, but it cannot describe the whole sea. Before downloading, test an app with a familiar coastal route and compare what it shows with your official marine forecast.

1. Can you inspect more than your current location?

A forecast at your phone's position may say little about the headland, channel or destination ahead. Check whether you can choose a point on a map or a place along your intended passage. Then look at the hours that matter for departure and return. A broad regional forecast remains important: one point forecast does not represent an entire operating area, as the US National Weather Service notes.

MARLOG lets you choose a marina or point from its Atlas, search or map and load a forecast for that location. That is useful for exploring a passage, but it is still a forecast for a selected point, not a complete route assessment. See how MARLOG Forecast works.

2. Does it show the sea as well as the wind?

Look for gusts and wave information alongside wind speed. Some services also show wave direction and period. Those details matter because locally generated wind waves and distant swell can combine into a sea state that a single wind number does not explain. ECMWF's wave-forecast explainer describes why forecasts use several wave measures rather than one.

In MARLOG, the Home sailing window presents up to 12 hours of wind readings. The full Forecast adds wave and other marine information for the selected point. The wind bars do not grade the safety of a departure hour. When choosing any app, check which values appear in a quick view and which require opening a fuller forecast.

3. Are the data sources and coverage clear?

An app should tell you which service supplies its atmospheric and marine data, where it offers regional detail, and where it falls back to broader coverage. This helps you understand why two apps can show different numbers for the same place. It also makes it easier to compare their output with an official source.

MARLOG says its atmospheric forecasts come from Apple Weather, its waves, sea temperature and currents from the EU's Copernicus Marine Service, and its home-port sea-state alerts from MET Norway. It describes higher-resolution regional marine models in the Mediterranean, Aegean, Marmara and Black Sea, with a global model elsewhere. These are MARLOG's published product descriptions, not a claim that one forecast source will always outperform another.

4. What exactly does an alert cover?

Read the alert's location and trigger. Is it for your current point, your home port, an official forecast zone or a planned route? Those are different services. MARLOG's published Forecast page describes sea-state checks around a set home port every three hours. That should not be read as a promise to monitor every point along a passage.

An app notification can be useful, but it should prompt you to open the latest official warning and forecast for the relevant waters. It should not become the only way you learn that conditions have changed.

5. Can you understand it quickly, and can you verify it?

Try a familiar destination. Can you find the wind trend, gusts, wave information and update time without guessing what a colour means? Can you reach the underlying marine source or at least identify it? If you plan to sail beyond mobile coverage, also check what the app actually keeps available offline; do not assume a forecast remains current without a connection.

Finally, compare the app's picture with official forecasts and real observations on several different days. A useful app makes the weather easier to inspect and discuss. It cannot remove uncertainty or make the departure decision for you.

Explore MARLOG Forecast or get MARLOG for iPhone.

Sources: MARLOG Forecast features and limits; ECMWF on ocean wave forecasts; US National Weather Service marine FAQ. MARLOG product details were checked on September 22, 2026.