Wave, current and sea temperature forecast: what to check before heading out to sea
To know what the sea will be like, wave height is not enough. Its period also counts, where it comes from, whether the wind is with it or against it, the current and the tide. And all of that changes a lot from one beach to the next: a cove sheltered by a headland can be calm with a metre and a half of swell outside. AXPA Weather shows it on a single map, with the waves fitted to the real shape of the coast.
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In short
- Wave height alone is misleading: at the same metre, a 14-second period carries far more power than a 6-second one.
- The wave that reaches your beach depends on the shape of the coast: a headland or a bay reduces it a lot.
- With an offshore wind, wind against the waves cleans them up at the shore; out at sea, that same wind builds them up and makes them shorter and harsher.
- Forecast currents do not include the tide: always check the tide tables.
- In summer, in Galicia and Portugal, coastal water can be several degrees colder than offshore.
- In AXPA Weather you get wave height, period and direction, wind over the sea, currents and water temperature, free and with no account.
The four things to check
Significant wave height is the average of the highest third of the waves: it is what an experienced observer would estimate by eye. It is the first number, but not the only one.
The period is the number of seconds between one wave and the next. A long-period swell, 12 seconds or more, comes from a distant storm and carries a lot of energy: it breaks harder and runs further up the shore. A short-period wind sea is messier and more uncomfortable, but has less power.
The direction tells you which coasts take the waves head-on and which stay sheltered. And the wind over the waves tells you whether it blows against them, which builds them up and makes them harsher, across them, or with them, which smooths them out.
The wave at your beach, not twenty kilometres offshore
Global wave models work out the sea in cells of about 25 km, and the nearest sea point to many beaches is between 6 and 25 km from the shore. Out there are no headlands, no bays, no rias: only open sea.
AXPA KITE fits the waves to the real shape of the coast. It takes into account the shelter a headland or a bay gives depending on the direction of the swell, and the sea that the local wind raises over the water in front of it. The result is the wave that reaches your beach, in more detail the closer you get to the shore.
Drag the bar to compare both models at the same place and the same time.
Wind over the sea and on the coast
On the coast, the wind has its own rhythm. On sunny days, the sea breeze comes in during the afternoon and dies down at dusk; at night and in the early morning there is sometimes a land breeze, blowing from land to sea, which flattens the waves but carries anything floating away from the shore. In a strait or between two coasts, the wind is squeezed and blows harder than in open sea.
AXPA KITE works out the wind with the real shape of the coast, including the breeze, and on the map you see the mean wind and the gusts over the water.
Offshore or onshore: which side the wind hits your wave from
To surf, knowing how big the waves are is not enough: it matters which side the wind hits them from. With an offshore wind, blowing from land out to sea, the wave arrives clean, holds up longer before breaking and peels. With an onshore wind, blowing towards the shore, it falls apart and breaks in sections. And with a cross wind it gets choppy and loses shape.
The Wind over waves layer paints this along every stretch of coast: blue for wind against the wave (offshore, at the shore), orange for wind with it (onshore), yellow for cross. The harder it blows, the stronger the colour. Because the waves and the wind come from AXPA KITE, which works with the real shape of the coast, you can tell one beach from the next: on one side of a headland the wind can be offshore and on the other onshore, a kilometre apart.
Offshore the same colour reads the other way round: wind against the waves builds them up and makes them shorter and harsher, which is the last thing a boat wants. That is why the layer does not say good or bad; it says which side the wind comes from.
Drag the bar to compare both models at the same place and the same time.
Currents
The surface current moves a kayak, a board or a swimmer, and in a strait or at the mouth of a ria it can be strong. On the map you will see the current from a global ocean model, with the drift caused by the wind, and in the rias and bays that model cannot see, AXPA KITE adds the drift from the local wind.
Important: these currents do not include the tide. In rias, in estuaries and on many Atlantic coasts, the tidal current is what counts. Before heading out, always check the official tide table for your port.
Water temperature
Water temperature decides which wetsuit you wear, how long you can stay in the water and whether there is life to dive or fish for. And it is not the same all along the coast: in summer, the north wind in Galicia and Portugal brings deep, cold water up near the shore, known as upwelling, and the coast can be several degrees colder than offshore.
On the map you see the sea surface temperature for the next nine days, from a global ocean model. Inside rias and very enclosed bays, that temperature is less accurate than in open sea.
What to check for what you are going to do
For surfing, the height and above all the period and direction of the swell, with light wind or an offshore breeze. For sailing, windsurfing or kitesurfing, the mean wind and the gusts, and the wind over the waves. For kayaking and paddleboarding, the wind, the current and the tide, which can make getting back very hard. For diving and snorkelling, the waves in the cove, the water clarity the swell leaves behind and the temperature. For fishing, the waves, the wind and the water temperature.
And for a family swim, the waves at your beach and the current. If the red flag is up, the flag decides.
How accurate it is
These are AXPA KITE's figures at sea against the IFS from the European Centre (ECMWF), checked against buoys and coastal points. The wave figures are from the same period used to tune it, and we mark this on each card: out-of-sample verification is under way.
AXPA KITE at sea
Error against the IFS (ECMWF), at the same point and the same time. Lower is better.
Wind over the sea
−14% error
Root mean square error (RMSE)
Buoys held out of the calculation, in Europe. 48-hour test set.
Coastal breeze
−5% error
Mean vector error
786 coastal points held out of the calculation, 228,000 hours.
Wave height
−24% error
Root mean square error (RMSE)Tuning period
249 buoys worldwide, 3,126 comparisons, from 26 to 29 October 2026.
Wave height on sheltered coasts
−67% error
Root mean square error (RMSE)Tuning period
Buoys protected by a headland, a bay or an island, over the same period.
| Variable | IFS (ECMWF) | AXPA KITE |
|---|---|---|
| Wind over the sea | 2.58 m/s | 2.21 m/s |
| Coastal breeze | 2.40 m/s | 2.29 m/s |
| Wave height | 0.38 m | 0.29 m |
| Wave height on sheltered coasts | 0.81 m | 0.27 m |
Wind is measured out of sample, at buoys and coastal points held out of the calculation. Waves are compared with buoys that AXPA KITE does not use to calculate them, over the same period used to tune it; out-of-sample verification is under way. Measured in October 2026.
Sea layers
They are all on the same AXPA Weather map, with a slider to move through the coming hours and days.
What you can see of the sea
The sea and what moves it, on the same map.
Sea
For surfing, sailing, kayaking, diving, fishing and swimming.
- Wave heightAXPA KITE
- Wave height and direction, with the real shape of the coast: the shelter a headland or a bay gives.
- Wave period
- The seconds between one wave and the next. The longer it is, the more power the swell carries.
- Wind over wavesAXPA KITE
- Which side the wind hits the wave from: against (offshore, at the coast), cross or with it (onshore). Beach by beach.
- Water temperature
- Sea surface temperature for the next nine days.
- CurrentsAXPA KITE
- The surface current, with wind drift in rias and bays. Does not include the tide.
Wind
For cycling, sailing, paragliding or flying a drone.
- Wind and gustsAXPA KITE
- Mean wind and gusts at 10 m, with the effect of terrain, coast and breeze.
- Rain radar
- The rain falling now, with the last two hours every 10 minutes. In Europe.
- Storms
- Where conditions favour storms over the coming hours and days.
- Lightning
- Strikes from the last few minutes, seen from satellite.
Where each piece of data comes from
Which variables are published, where they come from, what AXPA KITE modifies and what is verified.
Sea technical sheet
What is published and what AXPA KITE does with each variable.
- Waves
- Significant height, peak period and direction. AXPA KITE corrects height and direction near the coast using the real shape of the coastline. It does not yet separate swell from wind sea.
- Wave resolution
- About 2.5 km, with more detail near the shore.
- Wave verification
- RMSE of significant height against 249 buoys, from 26 to 29 October 2026, which is also the tuning period. Out-of-sample verification is under way. Period and direction have no published comparison yet.
- Wind over the sea
- RMSE against buoys held out of the calculation, in Europe, on a 48-hour test set; vector error against 786 held-out coastal points.
- Water temperature
- Surface temperature from a global ocean model at 1/12° (about 9 km), up to about nine days ahead. AXPA KITE does not modify it. Inside rias and enclosed bays its error is larger, around 1 to 1.5 °C against buoys.
- Currents
- Surface current from a global ocean model, with wind drift and without tide. In rias and bays that model does not resolve, AXPA KITE adds the drift from the local wind. In open sea it matches the global model, checked with high-frequency radar on the Galician coast; inside the rias there is no verification yet.
- Tides
- Not published. Check the official tide table.
Frequently asked questions
See all questions- Where can I see the wave forecast for my beach?
- In AXPA Weather, free and with no account: search for your beach and open the sea layer. You will see wave height, period and direction hour by hour.
- What is wave period?
- The number of seconds between one wave and the next. The longer it is, the more energy the wave carries and the harder it breaks.
- What is swell?
- Waves generated by a distant storm that arrive orderly and with a long period, even when there is no wind on your coast.
- Does the forecast include tides?
- No. For the tide and tidal currents, check the official tide table for your port.
- Why is the water so cold in Galicia in summer?
- Because of upwelling: the north wind pushes the surface water away and deep, cold water rises near the coast.
- Does it work on any coast?
- Yes, on any sea in the world. The fit to the shape of the coast shows most where there are headlands, bays, rias or islands.
- Does it replace official warnings?
- No. For coastal storm warnings, the reference is your country's weather service.
- What is an offshore wind and why do surfers look for it?
- It is the wind that blows from land out to sea. It holds the wave up from the front, keeps it clean and makes it break later and more evenly. In AXPA Weather you see it in the Wind over waves layer, in blue, beach by beach.
Keep reading
The figures in this guide are real measurements over the periods and samples stated for each one, and they may change as the model evolves. The forecast is for information only: for official severe weather warnings, check your country's weather service.