Our wind figures
Where the numbers come from
Every spot page counts how often the wind has cleared a riding threshold, month by month and hour by hour. The counts come from the hourly history of the finest weather model that reaches that beach. Each page names its model, its resolution and its years in the Sources list at the foot of the page.
A model is not a measurement. So we check each spot's figures against something independent of the model wherever we can, and we tell you when we have not.
Checked against a weather station
Where a weather station stands on or near the shore, within 10 km and open to the same wind, we hold the model's record against the station's own readings over the years they share. If the model reads too high or too low there, we correct it month by month and hour by hour, and we keep a correction only when it does better on years it was not fitted to.
A month publishes only when its figure holds to within 10 points of the share of rideable days against the station. A month that does not is left blank rather than guessed. A person on our team then reviews each station check and signs it off.
Some spots have no station near enough, but a second, independent climate model (ERA5) agrees with the record to within 10 points, month by month on average, over the same years. We treat that as a check too.
Not yet checked
When no station is near enough and no independent model agrees, the figures come from the finest model that reaches the spot, and nothing independent has confirmed them yet. They are still our best reading of the place. The spot page says so in one line beside the month's figures, and you should treat them as a guide.
When we hold the figures back
Sometimes the record cannot stand on its own: there is no station check, and the model's nearest point is more than 5 km from the beach, or more than half of the months are too uncertain to publish, or a month rests on fewer than three years. We also hold the figures back when the written sources show the record missing the wind riders go there for, whatever the models say. Those pages show no rideable-day figures, say why, and are not indexed by search engines.
Thresholds by sport
Kite 12 kt, windsurf 13 kt, wing 12 kt.
Each threshold is the mean wind at which that sport becomes rideable for one reference rider: an adult of about 75 to 80 kg, riding at intermediate level, on the light-wind end of a common quiver. For kite that is a 12 to 14 m kite on a twin tip; for windsurf, a 7.0 to 7.8 m² sail on a 130 to 150 litre freeride board, planing; for wing, a 5 to 6 m² wing on a mid-size foil, front wing about 1,500 to 2,000 cm². We set each number from the manufacturers' wind-range charts and from school and rider guides for that weight and kit.
A wing foiler gets going in less wind than a windsurfer needs to plane. Kite and wing need about the same wind for this rider, so their figures are the same. If you are lighter or ride bigger kit, you will ride in less wind than this; if you are heavier or ride smaller kit, you will need more.
How we count a rideable day
A day is rideable when the model's wind at 10 metres is at or above the sport's threshold for at least three hours of daylight, counted hour by hour from 06:00 to 19:00 local time.
We count the model's hourly wind speed, which is a mean over the model's grid, not the gusts. Forecasts give the mean wind too, so you can hold a forecast against these thresholds. Spot pages show the month's strongest gust separately.
A month's figure is the share of its days that are rideable, averaged over every year in the record. "24 rideable days in 30" is that share of a 30-day month.
Why one model does not check another from the same centre
ERA5 and the ECMWF IFS forecast model both come from the European Centre for Medium-Range Weather Forecasts and share much of their make-up. When the two agree, that proves little, so a spot whose record comes from ECMWF IFS counts as not yet checked until a station checks it.
What you see on a spot page
Every figure carries a tag. Record means it was counted from the spot's wind record. Modelled means it was computed because no measurement exists yet, and a line beside it says why. Written means it is our own editorial reading of the place. A page whose figures are not yet checked adds one line under the month's figures saying so, and the Sources list names the model, the years and any station the figures were checked against.
Something looks wrong?
If you ride a spot and its figures do not match what you see on the water, tell us: hello@windchaser.ai. We check every note against the record and correct the page.