Windchaser Forecast →

How it works

Windchaser doesn’t tell you what the wind is doing: it tells you when you can go out at your spots, how long until then and how many hours it will last. It reads the forecast hour by hour and looks for windows: daylight hours in a row with the wind above your threshold. It works for windsurfing, kitesurfing, wing foiling, windfoiling and foiling, and for anything else that runs on wind.

Where the data comes from

Everything comes through Open-Meteo. The server checks every 15 minutes and downloads the forecast when a new run is out: AROME HD every 3 hours, ECMWF and GFS every 6 and the sea every 12. The footer of the forecast shows the run of each model; if one is late, it says so.

For each hour, the finest model with data wins. From day 7 to 16 there are only global models: it is a trend, not a forecast to make plans with.

The windows are worked out by Windchaser from this data (source: Météo-France, ECMWF and NOAA/NCEP). They are not the original model data, and none of these organisations endorses Windchaser.

How to read it

The big number
The average wind in knots. At first, that of the next window (or of the one already under way); if you drag the timeline, that of the hour you pick. Next to it, Beaufort. Behind it, the name of the wind.
Below the number
Wind, sky and sea. The wind says where it blows from and whether it is slightly gusty, gusty or very gusty; the bar runs from minimum to maximum, with a mark at the mean, the dashed line of your threshold and the diamond of the gust. The sky says what it will be like and the chance of rain (below 10 % it is not shown). The sea gives the swell that reaches the beach, with its period (the longer, the cleaner and more powerful), the wind sea and the tide. For a window, everything covers the whole session: the sky that lasts the most hours, the highest chance of rain and the biggest sea. For the hour you pick, just that hour.
The rose
The needle points where the wind is going. The arcs are the spot’s sectors: green is good, yellow is neutral and magenta is offshore, wind from the land that pushes you out to sea. Offshore windows are flagged. Inside, the hour you are looking at as a chart of the sky and the sea: the golden dot is the sun (the ring is the horizon and the centre is straight above you) and the dots are its path for the day; the arcs coming in from one side are the swell that reaches the beach, reaching further in the bigger it is and more spaced the longer the period; and, where there is tide, the light line is the water’s edge between high tide (the coast) and low tide (the dotted line), with a small arrow when it is rising or falling. The values are under the big number.
Settings
The “≥ 12 kn” button at the top opens the settings. The minimum wind is the average wind you go out from (12 kn by default): it applies to every spot and changes every window. The days are the days of the week you can go out: sessions and alerts only count those days, and the timeline dims the rest. You also pick your spots and turn on alerts there.
Windows
Daylight hours in a row with the average wind above the threshold, at least 2 hours long. One light hour in the middle does not cut the session; a change of sector (from good to offshore, for example) does. Night hours do not count.
The timeline
The daylight hours of the next 7 days. Solid bars reach the threshold, the shade above them is the gusts and the dashed line is the threshold. Drag it to see any hour; let go and it goes back to the next window. ▶ plays the week. Forecast times are local to each spot. When they differ from your device’s, the time zone is shown (for example, “Portugal time”).
All and Mine
“All” combines every spot and, for each hour, shows the best one: first those that reach the threshold without offshore wind. If you pick your spots (the + at the end of the bar or the settings), it becomes “Mine” and only counts those. It is saved in this browser; “Copy the link” takes it to another device.
Right now
Where there is a weather station, the wind of the last 10 minutes against what the forecast said. And the webcams nearby, which open full size with a tap.

Alerts

Alerts are turned on in the settings (the bell at the top takes you there) and are for this device. You get one when a new window shows up at your spots on the days you can go out, when one you were already told about clearly improves (3 kn more on average or 2 hours longer) and the evening before. Only windows without offshore wind, within the next 5 days and with at least 2 hours still to go. From 22 to 8 h, silence. On an iPhone you first need to add the app to the home screen; the settings explain how.

If you would rather not turn anything on, there are Telegram channels with the same alerts for everyone:

The tramontane recommender

On tramontane days the wind blows across the whole area, but not the same everywhere. The recommender looks at how the day will go and tells you which spot to head for, today and tomorrow. It shows up as a strip under the spots bar if more than half of your spots are in the area (Llançà, Port de la Selva, Sant Pere Pescador, La Rubina and La Franqui) or if you are looking at one of them. The arrow at the end opens the details: the reason, the indicators, the hours and the run it comes from.

Llançà is the reference and is never recommended. If the wind there blows from the north for most of the daylight hours, it is a tramontane day, and the recommender picks the first of these cases that applies:

The cases come from the gradient and stability, worked out over the daylight hours (for today, the ones left). The detail also shows you the gusts and the sea:

The gradient and stability have thresholds, and right next to one the case is not clear. If none is close, confidence is high and it names one spot. If one is, confidence is medium and it suggests a second, the one from the neighbouring case. If two or more are, or AROME HD is missing, it stays quiet: it says the day is unclear and shows you the indicators so you can decide. If the day splits (strong in the morning and light in the afternoon, for example), the longest stretch wins, and it tells you the hours.

It only looks at today and tomorrow, and the thresholds are still being tuned as the days go by. On strong days the models fall short: expect more wind than they say. And at La Franqui the tramontane blows offshore: do not go out alone.

The background

The background is not decoration. Everything moving in it comes from the forecast for the hour you are looking at.

If reduced motion is on in your system, the background stays still.

The spots

Yours is missing? Ask for it.

What it does not do

Windchaser is a forecast, and forecasts get it wrong. A sea breeze that never fills in, a storm that swings the wind or a local effect the model cannot see will not show up anywhere. Before loading the car, check the station and the webcam. And on the water, trust what you see and the locals.

The tramontane recommender is not a general recommender: outside that area it says nothing.

Anything you would improve or tweak? Tell us.

Frequently asked questions

Where does the wind data come from?
From Météo-France AROME HD (1.3 km, first two days in Catalonia and France), ECMWF IFS (9 km, up to 15 days) and NOAA GFS (up to 16 days), all through Open-Meteo. The sea comes from Open-Meteo Marine. For each hour, the finest model that has data wins.
What is a window?
A run of daylight hours with the mean wind above your threshold (12 kn by default), at least 2 hours long. One weak hour in the middle does not end the session; a change of sector does. Night hours do not count.
What does offshore mean?
The wind blows from land out to sea. It pushes you away from the shore and, if your gear fails, can carry you out. Windchaser shows each spot’s offshore sectors in magenta and flags the windows that have it.
How do alerts work?
You turn them on in the options and they are for this device. They tell you when a new window appears at your spots, on the days you can go out, when an already announced one clearly improves, and the evening before. Only windows without offshore wind in the next 5 days; silent from 22:00 to 08:00. There are also Telegram channels per area with the same alerts for everyone (the link is in the options and on each spot’s page).
How far can I trust the forecast?
Forecasts get things wrong: a thermal that does not kick in or a local effect the model cannot see will not show up. From day 7 to 16 there are only global models, so it is a trend, not a forecast to plan around. Before you go, check the station and the webcam.