Why Wind Can Be Stronger at 120 m Than at Ground Level
The launch site feels calm. The trees barely move. You climb to 100 m and the drone starts leaning hard, drifting, and the app warns about strong wind. Nothing changed — you simply flew into the wind that was there all along.
Nearly every forecast and weather station quotes wind at 10 m above ground. Drones regularly fly at 50–120 m. The wind at those heights is usually stronger and can come from a different direction. Check it for your location with the Wind at Altitude tool, which shows forecast wind at 10, 80, 120 and 180 m.
Why wind increases with height
The ground slows the air. Grass, crops, hedges, trees and buildings all create friction, and that drag is strongest at the surface. Each layer of air slows the layer above it a little less, so wind speed rises with height through the lowest few hundred metres — the boundary layer.
Meteorologists describe this with a wind profile. A common approximation, the power law, says:
wind at height h = wind at 10 m × (h / 10) ^ α
The exponent α depends on how rough the ground is and how stable the air is.
| Surface (neutral conditions) | Typical α | Wind at 120 m vs 10 m |
|---|---|---|
| Open sea, lakes | 0.10 | about 1.3× |
| Open farmland, grass | 0.14 | about 1.4× |
| Scattered trees, villages | 0.20 | about 1.6× |
| Towns, forests | 0.25 – 0.30 | about 1.9 – 2.1× |
A rougher surface slows the wind near the ground more, so the ratio between 120 m and 10 m grows. Over a town, 10 km/h at street level can be 20 km/h at 120 m.
When the difference is largest
The ratios above are for a well-mixed atmosphere. The real difference changes through the day.
Clear, calm nights and early mornings. The ground cools and chills the air right above it. That cold layer — a temperature inversion — becomes stable and stops mixing with the air above. Surface wind can drop to almost nothing while the wind at 100–300 m keeps blowing, sometimes strengthening into a nocturnal low-level jet. At dawn the 120 m wind can be three or more times the surface wind. This is the classic trap: a perfectly still sunrise with a brisk wind at photo height.
Sunny afternoons. Heating stirs the lower atmosphere with thermals. That mixing brings faster air down, so surface wind picks up and the difference between 10 m and 120 m shrinks — but gusts grow. See wind speed vs gusts.
Near hills, cliffs and ridges. Air speeds up as it's squeezed over a crest, so a hilltop at 120 m above the valley may see much more wind than the profile suggests. The lee side can bring sinking air and rotors.
Direction changes with height too
Friction also turns the wind. Near the ground, it blows more across the pressure pattern; higher up it lines up with it. In the Northern Hemisphere the wind usually veers (turns clockwise) with height — often by 20–40° between the surface and a few hundred metres over land. In the Southern Hemisphere it backs.
This matters because the return leg you planned as a crosswind may turn into a headwind at height. The Ground Speed Calculator works out ground speed and crab angle for the wind at the height you choose.
Wind shear: when the change is sudden
A gradual increase with height is normal. A sharp change across a thin layer — often at the top of an inversion — is wind shear. Climbing through it, the drone meets a sudden change in wind speed or direction and may lurch or drift. UAV Meteo flags shear between 10 m and 120 m in the flight rating; the wind shear guide explains what to do about it.
How to check the wind at your flying height
- Look at the forecast at 80 and 120 m, not just at 10 m. The Wind at Altitude tool and the dashboard's wind-by-height panel show both.
- Compare it with your drone's limit, keeping a margin. The Drone Wind Calculator does the comparison.
- Watch clouds and treetops. Low clouds racing across the sky or tall trees swaying while the ground is calm are signs of wind aloft.
- Climb in steps. Hover at 30 m, then 60 m, and watch how hard the drone leans and how its ground speed changes on a short leg. If it's already struggling at 60 m, it won't improve higher up.
- Keep the return leg in mind. If the wind at height is a headwind on the way home, that leg is slower and uses more battery. The Return-to-Home Calculator checks whether your battery covers it.
FAQ
How much stronger is wind at 120 m than at ground level?
Over open ground in the daytime, typically about 1.3 to 1.5 times the 10 m wind. Over towns or forests it can be twice as strong, and on calm clear mornings three times or more.
Why does the forecast show wind at 10 m?
It's the international standard height for measuring wind, used by airports and weather services. Forecasts are verified against those measurements, so 10 m is the default number most apps show.
Is it safer to fly lower in wind?
Usually the wind is lighter lower down, but you're also closer to obstacles and their turbulence. Fly high enough to stay clear of trees and buildings, and no higher than you need.
Related: what wind speed is safe for a drone and how to read a weather forecast before flying.
Sources
- R. B. Stull, An Introduction to Boundary Layer Meteorology (Springer, 1988) — wind profiles, stability and the nocturnal low-level jet.
- World Meteorological Organization, Guide to Instruments and Methods of Observation (WMO-No. 8) — the 10 m standard height for wind.
- Forecast data at 10, 80, 120 and 180 m: Open-Meteo, as listed on our Data Sources page.
This guide is general information for planning, not aviation regulation.