In short
Open-Meteo gives a marine forecast about two weeks ahead. For sea days we take a point halfway between the neighbouring ports; for port days, the port itself. Waves under about 1.25 m are barely felt on a big ship; from 2.5 m many people notice the motion; from 4 m the captain may change course or speed. For dates further away you see what is usual for that month.
Updated: October 2026
Route by day
How it works
- Choose the boarding day, the number of nights and a port or «Day at sea» for every day — the same way as in the cruise planner.
- For a port day we look at the sea right next to the port; for a sea day, at a point between the previous and the next port. It is an approximation: the real course may run closer to the coast or further out.
- Up to about two weeks ahead you see the forecast: wave height, swell, wind and gusts, the maximum of the day. Further ahead, how the sea usually is in that month, from data for 2021–2025.
- In ports where passengers often go ashore by tender, we flag days with strong gusts or high waves: those are the days when tender landings are sometimes cancelled.
- The link keeps your route: save it and open it again a few days before departure — the forecast will have updated.
What the levels mean
| Level | Waves | What it usually feels like |
|---|---|---|
| Calm | under 1.25 m | A large ship barely moves. Most people feel nothing. |
| Light motion | 1.25–2.5 m | A slow, gentle sway, more noticeable at the bow and on high decks. Sensitive people may feel it. |
| Noticeable motion | 2.5–4 m | Many people notice it; seasickness is possible. Outdoor pools and some open decks may be closed. |
| Rough | over 4 m | Walking is easier with a hand on the rail. The captain may change speed, course or the order of ports. |
If you are prone to seasickness
- A cabin in the middle of the ship and on a lower deck moves least — see where on the ship.
- On a rocky day: fresh air, eyes on the horizon, light food, less alcohol.
- Ask a doctor or pharmacist about seasickness remedies before the trip — most work best when taken in advance.
- Modern cruise ships have stabilisers: the same waves feel much softer than on a ferry.
Common questions
How accurate is the forecast?
For the next 3–5 days it is usually quite reliable; a week or more ahead, treat it as a trend. Wave height here is the significant height (the average of the highest third of waves), the maximum for the day — single waves can be higher.
Why does a sea day show a point between two ports?
We don't know the exact course the ship will take. Halfway between the neighbouring ports gives a fair picture of that stretch of sea; near the coast and in sheltered waters it is often calmer than shown.
My cruise is months away. What do I see?
Typical values for that month: the usual wave height and roughly how many days a month have waves of 2.5 m or more. The real forecast appears about two weeks before the dates — open the same link then.
Can a port call be cancelled because of the weather?
Yes, the captain decides. It happens most often in tender ports — where the ship anchors and passengers go ashore by boat — in strong wind or waves. What happens next is in our guide to port changes.
Which ships move less?
As a rule, larger ships with stabilisers. But a lot depends on the direction of the waves relative to the course and on where your cabin is.
Where does the data come from?
From Open-Meteo, which combines the wave models of several national weather services. It is a forecast, not a promise: the latest weather information is always on board.
Also useful
This is an information tool. Forecasts change; the captain and the cruise line decide on the route and port calls. Weather data: Open-Meteo.com (CC BY 4.0).