Wind at altitude calculator
Weather forecasts give wind at 10 m. Here is roughly what that becomes where your drone flies.
How it works
Near the ground, friction slows the wind. The standard power law estimates the wind higher up: v(h) = v10 × (h / 10)^α. The exponent α is about 0.14 over open land by day and 0.20–0.30 at night or over towns and forest, when the air near the ground is calmer and the wind higher up is decoupled from it.
Gusts aloft are estimated by adding the 10 m gust excess (gust minus mean wind) to the wind at each height: near the ground the size of a gust above the mean changes much less with height than the mean wind does. The estimate is never below 1.2× the wind at that height or below the 10 m gust. They are estimates: no forecast model gives gusts at 120 m. In the app Altiwind uses the model’s own winds at 10, 80, 120 and 180 m when they exist, which beats this rule of thumb. More in how wind changes with height.
FAQ
How much stronger is the wind at 120 m?
Over open land by day, about 40% stronger than at 10 m (12^0.14 ≈ 1.42). At night or over towns it can be 1.9–2.1 times the 10 m wind.
Why does night make such a difference?
On clear, calm nights the air near the ground cools and stops mixing with the air above, so the surface goes quiet while the wind a hundred metres up keeps blowing.
Are the gusts exact?
No. Gusts at height are estimated by carrying the 10 m gust excess up to your height, and are always labelled as estimates.