The Beaufort scale for drone pilots

The Beaufort scale sorts wind into forces 0 to 12 by its mean speed 10 m above open ground. For drone pilots the key line is Force 5, "fresh breeze", which tops out at 10.7 m/s (24 mph, 21 kt). That is exactly the "Level 5" rating many small drones carry, so a Force 5 forecast can already put a mini drone at its maximum.

The full scale

Speeds are mean winds 10 m above open, flat ground, from the WMO's standard table. The last column applies Altiwind's default wind checks to two common ratings: 10.7 m/s (most sub-250 g minis) and 12 m/s (mid-size drones such as the DJI Air 3S), assuming the same wind at flying height. In reality it is usually stronger up there.

The Met Office's Beaufort table gives knots and rounded metres per second, so its m/s bands look slightly different from the WMO values above. The knot bands match.

Where "Level 5" comes from

DJI's spec page for the Avata 2 lists its maximum wind speed resistance as "10.7 m/s (Level 5)", and the Mini 4 Pro lists the same 10.7 m/s. That number is the upper edge of Beaufort Force 5. Ratings of 12 m/s, as on the DJI Air 3S, Mavic 4 Pro and Mini 5 Pro, fall inside Force 6.

Three things to keep in mind when you read a "Level 5" claim:

• It is the top of the band, not the middle. A Level 5 drone in a Force 5 wind may be anywhere from 75% to 100% of its rating.
• Beaufort describes the mean wind. Gusts can be well above it, and gusts are what push a drone around. See gusts vs sustained wind.
• Beaufort is measured at 10 m. Over open land the wind at 120 m is typically about 1.4 times stronger, and more on calm nights. A Force 4 at the ground can be a Force 5 or 6 at your flying height.

Our guide to drone wind limits by class compares ratings across drone types.

Reading the wind by eye

Beaufort was built on what you can see, and the WMO table still lists signs on land. They are a good sanity check against a forecast:

• Force 2: you feel the wind on your face and leaves rustle.
• Force 3: leaves and small twigs are always moving, and a light flag extends.
• Force 4: dust and loose paper lift, and small branches move.
• Force 5: small trees in leaf begin to sway.
• Force 6: large branches move and umbrellas are hard to use.
• Force 7: whole trees move and walking into the wind takes effort.

Remember that these signs describe the wind near the ground. Treetops swaying while your face feels little is a hint that the wind is picking up with height.

Using a Beaufort forecast

You will mostly meet Beaufort forces in marine and coastal forecasts, such as the Met Office's shipping and inshore forecasts. Land forecasts tend to use mph or km/h, and aviation uses knots. A typical marine line reads "west 4 or 5, occasionally 6".

To turn that into a drone decision:

1. Take the upper force, here 6, which starts at 10.8 m/s.
2. Remember it is a 10 m mean, so the wind at 120 m is likely stronger and the gusts higher still.
3. Compare it with your drone's rating. Force 6 is already beyond a 10.7 m/s mini's rating, and above 85% of a 12 m/s drone's rating.

Altiwind does these steps for you, with numbers at your chosen height, but the quick check above is handy when all you have is a coastal forecast.

Converting units

• 1 m/s = 3.6 km/h = 2.24 mph = 1.94 kt
• 1 kt = 0.514 m/s = 1.852 km/h = 1.15 mph

Altiwind shows wind in the units you choose and scores it against your drone's rating on the go/no-go score. For quick conversions, use the wind speed converter.

Sources

• Met Office, Beaufort wind force scale
• WMO, Guide to Instruments and Methods of Observation (WMO-No. 8), Volume I, Chapter 5, Table 5.1 (wind speed equivalents at 10 m and land signs)
• DJI spec pages for the Avata 2, Mini 4 Pro and Air 3S, checked October 2026