Riding in wind

The Beaufort scale for cyclists: what each wind force feels like

Turn any wind forecast, in forces, km/h, mph or knots, into what it will do to your ride.

By Wes Thomson, Founder, WindlinePublished 6 min read

The short answer

The Beaufort scale rates wind from force 0 (calm) to force 12 (hurricane). On a bike, forces 0–3, up to 19 km/h (12 mph), are comfortable; forces 4–5 make a headwind hard work; force 6, from 39 km/h (24 mph), brings risky gusts; and from force 7, 50 km/h (31 mph), most riders should stay home.

Key takeaways

  • Each force is a band of 10-minute mean wind at 10 m (33 ft), not a gust.
  • A force 4 headwind cuts a 25 km/h (15.5 mph) rider to 15 km/h (9.3 mph).
  • From force 6, gusts make handling risky; from force 7, most riders should stay home.
  • Most land forecasts use km/h or mph, so learn which force your numbers fall in.

Definitions

Beaufort force
One of 13 bands of mean wind speed, from 0 (calm) to 12 (hurricane), each with a description of the wind's visible effects.
Mean wind
The wind speed averaged over 10 minutes at 10 m (33 ft) above open, flat ground, the World Meteorological Organization standard.
Gust
The highest 3-second average wind speed within a period, measured separately from the mean.
Knot
One nautical mile per hour, or 1.852 km/h (1.15 mph), the unit used in marine and aviation forecasts.

What is the Beaufort scale?

The Beaufort scale sorts wind into 13 forces, from force 0 (calm) to force 12 (hurricane), each a band of speeds with a description of what that wind visibly does. This page is part of our guide to cycling in the wind.

Francis Beaufort, a Royal Navy officer, drew it up in 1805 for sailing ships (KNMI, the Dutch weather service). Descriptions of the wind on land came in 1906 (Hong Kong Observatory). Today a force is set by the mean wind: the 10-minute average, 10 m (33 ft) above open, flat ground, under World Meteorological Organization (WMO) standards.

What does each Beaufort force feel like on a bike?

Forces 0–3 barely change a ride, forces 4–5 make a headwind hard work, force 6 makes gusts a handling problem, and from force 7 most riders should stay home. Speeds and land descriptions are the WMO's; the bike column is ours.

Force Mean wind, km/h (mph) Knots On land (WMO) On a bike
0 Calm Under 1 (under 1) Under 1 Smoke rises vertically Your own speed is the only breeze
1 Light air 1–5 (1–3) 1–3 Smoke drifts Headwind costs up to 3 km/h (2 mph)
2 Light breeze 6–11 (4–7) 4–6 Leaves rustle Headwind costs 3–6 km/h (2–4 mph)
3 Gentle breeze 12–19 (8–12) 7–10 Light flags extended Comfortable; headwind costs 6–10 km/h (4–6 mph)
4 Moderate breeze 20–28 (13–18) 11–16 Dust and paper raised Hard work: into it, you drop to 12–15 km/h (7.5–9.3 mph)
5 Fresh breeze 29–38 (19–24) 17–21 Small trees sway Hard work: into it, 9–12 km/h (5.6–7.3 mph)
6 Strong breeze 39–49 (25–31) 22–27 Umbrellas hard to use Handling risk: gusts shove you sideways
7 Near gale 50–61 (32–38) 28–33 Walking into it is an effort Stay home: hard to cycle into (KNMI)
8 Gale 62–74 (39–46) 34–40 Progress impeded Stay home
9 Strong gale 75–88 (47–54) 41–47 Slates removed Stay home: children blown over (KNMI)
10 Storm 89–102 (55–63) 48–55 Trees uprooted Stay indoors: adults blown over (KNMI)
11 Violent storm 103–117 (64–72) 56–63 Widespread damage Stay indoors
12 Hurricane 118 or more (73 or more) 64 or more Severe damage (Canada) Stay indoors

Want this for your own route? Windline shows the wind for every stretch, timed to your pace. Free. Make a free ride page →

How much does each force slow you down?

More with every force, because drag rises with the square of the air speed hitting you. A rider who does 25 km/h (15.5 mph) in still air, at about 97 W, drops to 15 km/h (9.3 mph) into a 20 km/h (12 mph) force 4 headwind. Holding 25 km/h there takes about 248 W; into a 40 km/h (25 mph) force 6 wind, about 485 W, five times the effort.

These come from the standard road-cycling power model (Martin et al., 1998), with the rider from our headwind numbers. They're worst cases: wind at rider height is usually weaker than the forecast.

At which Beaufort force should you stop riding?

For most riders on open roads, force 7, a mean wind from 50 km/h (31 mph), is the stay-home line. Force 6 is where you shorten the ride or find shelter, because of gusts.

Australia's Bureau of Meteorology warns that gusts can be 40% stronger than the mean, so a force 5 mean of 30 km/h (19 mph) can gust to about 42 km/h (26 mph), force 6 strength. The UK Highway Code (rule 232) warns that strong gusts can blow a cyclist off course. Germany's weather service, DWD, starts its wind warnings at gusts above 50 km/h (31 mph), which it labels force 7.

Our decision table for windy rides covers gusts and what lowers your personal limit. Official warnings override all of it.

How do weather services around the world express wind?

Mostly in km/h, mph or knots, so you'll usually turn a number into a force, not the reverse.

  • UK: the Met Office's shipping forecast gives wind force for 31 sea areas, with gale warnings from force 8. Its land forecasts use mph.
  • US: National Weather Service forecasts use mph: "West wind 10 to 17 mph" (San Francisco).
  • Canada: Environment and Climate Change Canada uses km/h: "Wind west 30 km/h gusting to 50" (19 mph, gusting to 31 mph) for Toronto.
  • Belgium and Germany: Belgium's weather service, RMI, forecasts in Beaufort forces; DWD gives km/h with the force alongside.
  • Australia: land warnings in km/h, marine wind maps in knots.
  • Hong Kong: forecasts give a force, such as "East to northeast force 4".
## What mistakes do riders make with the Beaufort scale?

Most come from reading a force too literally.

  • One force, one speed. Force 5 spans 29–38 km/h (19–24 mph); the top of a band rides very differently from the bottom.
  • One scale everywhere. Knot bands are shared, but the Hong Kong Observatory starts force 6 at 41 km/h (25 mph), not the WMO's 39 km/h (24 mph).
  • Forgetting gusts and direction. A force describes the mean, not the gusts, and a force 4 tailwind is a gift. Check the wind direction against your road.

How do you use the Beaufort scale before your next ride?

Use it as a quick translation, then check your own roads and hours.

  1. Check for official wind warnings. If one covers your route, don't ride there.
  2. Turn the mean wind and the gusts into forces, and use the worse row.
  3. Find the stretches that face the wind, and when you'll reach them: see reading a forecast for a bike ride.
  4. Force 4–5: plan direction and pace. Force 6: shorten, find shelter or ride indoors. Force 7 and above: stay home.

Frequently asked questions

Is force 5 too windy to cycle?

Not usually, but it's hard work. A force 5 mean wind is 29–38 km/h (19–24 mph). In our model, a rider who does 25 km/h (15.5 mph) in still air drops to 9–12 km/h (6–7 mph) riding straight into it. Gusts can be 40% stronger than the mean, says Australia's Bureau of Meteorology, so expect force 6 gusts on exposed roads.

What Beaufort force is a gale?

Force 8: a mean wind of 62–74 km/h (39–46 mph), or 34–40 knots, which the WMO says generally impedes progress. The Met Office issues gale warnings for winds of at least force 8, or gusts of 43–51 knots, about 80–94 km/h (49–59 mph). Force 7 is a near gale.

How do you convert knots to km/h or mph?

Multiply knots by 1.852 for km/h, or by 1.15 for mph, the factor the Met Office gives. So 20 knots is about 37 km/h (23 mph), which is force 5. A force is a band, not one number, so use the table on this page.

Why does a gentle breeze feel so strong on a bike?

Because you feel your own speed plus the wind. Ride at 25 km/h (15.5 mph) into a force 3 wind of 15 km/h (9 mph) and the air meets you at 40 km/h (25 mph), a force 6 speed. Drag rises with the square of air speed, so it pushes back about 2.6 times as hard as in still air.

Does the Beaufort scale apply to gusts?

Officially, no: the WMO and the Dutch weather service KNMI define each force by the 10-minute mean. But Germany's DWD labels gusts above 50 km/h (31 mph) as force 7 in its warnings. When a forecast quotes a force, check whether it means the mean or the gust. On a bike, the gust usually decides.

Get the wind for your ride.

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Sources and method

  1. World Meteorological Organization (2008). Guide to Meteorological Instruments and Methods of Observation (WMO-No. 8), 7th edition, Part I, Chapter 5 (Measurement of surface wind), wind speed equivalents table
  2. Met Office (2026). Beaufort wind force scale
  3. Met Office (2026). Guide to marine forecasts
  4. Met Office (2026). Marine forecasts glossary
  5. Met Office (2026). London (Greater London) weather forecast
  6. Environment and Climate Change Canada (2017). Beaufort wind scale table
  7. Environment and Climate Change Canada (2026). Toronto, ON 7 day forecast
  8. US National Weather Service (Miami–South Florida office) (2026). Beaufort wind scale
  9. US National Weather Service (2026). Point forecast, San Francisco, California
  10. KNMI (Royal Netherlands Meteorological Institute) (2026). Windschaal van Beaufort
  11. Royal Meteorological Institute of Belgium (KMI) (2026). Beaufortschaal
  12. Deutscher Wetterdienst (2026). Warnkriterien (warning criteria)
  13. Bureau of Meteorology (Australia) (2026). About model forecast wind
  14. Bureau of Meteorology (Australia) (2026). Severe weather and coastal hazard warning services
  15. Hong Kong Observatory (2026). Beaufort wind scale
  16. Hong Kong Observatory (2026). 9-day weather forecast (text version)
  17. UK Department for Transport (2026). The Highway Code, rule 232 (windy weather)
  18. Journal of Applied Biomechanics (1998). Validation of a mathematical model for road cycling power (Martin, Milliken, Cobb, McFadden and Coggan)

Beaufort speeds and land descriptions are from the wind speed equivalents table in WMO-No. 8 (7th edition, 2008), where km/h, mph and knot bands are each rounded separately, so band edges don't convert exactly; they match the bands in our articles how-windy-is-too-windy-to-cycle and cycling-in-wind. Knot bands match the Met Office, Environment and Climate Change Canada and the US National Weather Service tables. WMO gives no land description for force 12, so that row uses Environment and Climate Change Canada's. Land descriptions are shortened. The "on a bike" column is ours: the Comfortable, Hard work, Handling risk and Stay home rows follow the decision table in how-windy-is-too-windy-to-cycle, and the speed losses come from the standard road-cycling power model (Martin et al., 1998) with the rider from how-much-does-a-headwind-slow-you-down: rider 75 kg + bike 9 kg + kit 2 kg = 86 kg (190 lb), drag area CdA 0.32 m², rolling resistance coefficient 0.005, air density 1.225 kg/m³, drivetrain efficiency 97.5%, flat road, no drafting, wind straight on the nose at its full 10 m strength, holding the effort that gives 25 km/h (15.5 mph) in still air (about 97 W). Losses in the table run from the bottom to the top of each force's km/h band (force 4: 20–28 km/h gives 15.0–12.0 km/h; force 5: 29–38 km/h gives 11.7–9.1 km/h). Power to hold 25 km/h is solved from the same model: 248 W into 20 km/h and 485 W into 40 km/h, against 97 W in still air. The force 3 example uses a 15 km/h wind: air speed 25 + 15 = 40 km/h, and (40/25)² = 2.56. The gust example multiplies a 30 km/h mean by 1.4 (42 km/h), from the Bureau of Meteorology's note that gusts can be 40% stronger than the mean. Conversions: 1 knot = 1.852 km/h (definition of the international nautical mile, 1,852 m); knots to mph × 1.15 (Met Office); 1 mile = 1.609 km.

Related reading

About the author

Wes Thomson, Founder, Windline. Wes Thomson builds Windline, live wind and weather forecasts timed to when riders reach each stretch of road. He built it for his own 2,093 km tour from Pont Drift to Cape Town, and writes these guides with the same focus: what the wind will do to your ride, and how to plan around it.