Read three numbers together: wave height, swell period and wind direction. For a boat trip along Madeira's south coast, a swell under about a metre with a long period and a wind from the north or north-east usually means a smooth ride, while swell or wind from the west or south-west is the warning sign.
Which three numbers should you look at first?
Wave height, wave period and wind direction. Each one alone can fool you. Read together, they tell you how the sea will feel on a small boat, not just how it looks on a map.
Most apps show significant wave height. It is roughly the average of the highest third of the waves, not of all of them. So most waves will be smaller than the number on the screen, and now and then a single wave can be close to twice that height. A forecast of 1 metre means mostly gentle water, with a few sets that make you hold on to your glass.
The period is the time in seconds between one crest and the next, and it matters as much as the height. Short-period waves of 5 or 6 seconds are chop raised by the local wind: steep, close together, bumpy. Long-period swell of 12 seconds or more comes from a storm far out in the Atlantic. It rolls in as long, smooth hills, but it carries far more energy, bends around headlands and breaks hard on rocks.
Then the wind. Forecasts give the direction it blows from, an average speed and the gusts. The gusts are what you feel on deck.
Why does direction matter so much in Madeira?
Because the island is a wall. The usual wind is the north-east trade wind, and the biggest Atlantic swells arrive from the north and north-west. Both hit the north coast first. The south coast, from Funchal west to Ponta do Sol, sits behind a mountain ridge that reaches 1,862 metres at Pico Ruivo.
So a forecast that sounds rough can still mean a fine morning on the south side, if it comes from the north. And a forecast that sounds small can make a poor day if it comes from the west, south-west or south, because nothing stands between that sea and the cliffs of Cabo Girão. The full picture is in why the south coast is calmer than the north.
What do the numbers usually mean on the south coast?
Take this as a rough guide, not a rule. It describes how the sea typically feels on a small motor boat between Funchal and Ribeira Brava. The skipper's look at the real sea always wins.
| What the forecast shows | What it usually means |
|---|---|
| Swell under 1 m, period 10 s or longer, light wind from the north or north-east | Smooth water along the cliffs, easy swim stops |
| Swell of 1 to 1.5 m from the north or north-west, moderate north-east wind | Often still pleasant west of Funchal, breezier towards the ends of the island |
| Short-period waves from the east or south-east | Choppy and splashy, more so on the run home |
| Swell of 2 m or more from the west or south-west | Rough on the south coast, often a day to stay in port |
For scale: Two recent examples: a yellow IPMA warning for the south coast in March 2025, for waves of 4 to 5 metres from the west, and an orange one in December 2025, with westerly waves forecast to reach maximum heights of up to 10 metres. Days like those are an easy call.
Which forecast should you trust: IPMA, Windy or an app?
Use more than one, because they do different jobs.
- IPMA, Portugal's weather service, issues the official warnings. Madeira is split into four zones: north coast, south coast, mountain areas and Porto Santo. Yellow means a risk for some weather-dependent activities, orange a moderate to high risk, red an extreme one. For a trip from Funchal, look at the south coast, "Costa Sul".
- The Capitania do Porto do Funchal, the local maritime authority, puts out its own warnings for rough sea and strong wind, and often extends them while a storm passes.
- Windy shows global models such as ECMWF and GFS on a map. It is the easiest way to see where a swell comes from and when it arrives, several days ahead. Its grid is coarse next to a steep island, so it can miss how sheltered the water is close under the cliffs.
- MadeiraOcean, a free app from the Oceanic Observatory of Madeira, forecasts waves, wind, currents and tides at more than 30 points around the island. Its makers call it experimental, which is honest: treat it as one more view.
The official warnings are on the IPMA website. If two models disagree, take that as a sign the forecast is uncertain, not that the nicer one is right.
How do you check the sea the evening before?
Give it five minutes and go in this order.
- Open the IPMA warnings for the south coast on your date. Orange or red for sea or wind: expect the trip to move.
- Look at the wind for the hours you will be out, not the daily average. A trip leaving at 10:00 and one leaving at 14:00 can meet different seas.
- Read swell height, period and direction together. Note anything from the west, south-west or south.
- Compare two sources. When they agree, trust the picture more.
- Check again in the morning. Tomorrow's forecast is usually far better than one for five days away.
What does the skipper see that an app cannot?
The real sea. From Marina do Funchal, a skipper can watch how the swell breaks on the harbour wall, how often the bigger sets come and whether the wind is already ruffling the bay. Local experience says which headland kicks up a short chop and which cove stays flat on a north-west swell. No model has that detail.
On Chifbay trips the rule is short. Our skipper still has the final word, and a trip called off for the sea means a new date or a full refund. Your own cancellation costs nothing if it comes 24 hours or more before departure. Everything else you need on the day, from the meeting point to what to bring, is on our practical information page.
When is a good forecast still not enough?
When you are prone to seasickness. A long, low swell can feel lovely while the boat is moving and still roll it gently at a swim stop, which is exactly when sensitive stomachs complain. If that is you, prefer days with swell under a metre, choose the shorter Day Trip of 2h30, and read our tips on avoiding seasickness on a boat trip.
The same goes for swimming. The Chifbay Day Trip swims at Fajã dos Padres and Ribeira Brava, two stony shores where a sunny forecast with south-west swell can still send waves over the stones. The boat may go out and the coast will look superb, while the swim waits for a calmer day.
Frequently asked questions
What wave height is too big for a small boat trip in Madeira?
There is no single number. Direction and period matter as much as height. A 1.5 metre swell from the north can leave the south coast calm, while 2 metres from the south-west makes it rough. The skipper decides on the day.
Is IPMA or Windy better for Madeira?
Use both. IPMA gives the official warnings for the south coast. Windy shows where swell and wind come from and when they arrive. Neither replaces a look at the real sea.
What does a swell period of 12 seconds mean?
The crests are 12 seconds apart. That is a long-period swell from a distant storm: smooth on the open sea, but powerful when it meets rocks or a beach.
How far ahead can you trust a sea forecast?
The next day is usually reliable. Three to five days out, read it as a trend. Check again on the evening before and on the morning of your trip.
Height tells you how big. Period tells you how hard. Direction tells you whether the island has your back.