Wind · 5 min read

The Beaufort Wind Scale Explained

By Emma Clarke · July 20, 2026

Wind speed on its own is just a number. The Beaufort scale turns that number into something you can actually picture, based on what the wind visibly does around you.

What is the Beaufort scale?

Devised in the early 19th century by Royal Navy officer Francis Beaufort, the scale runs from 0 (completely calm) to 12 (hurricane force), and describes how wind behaves at each level rather than just how fast it is. At force 3, leaves and small twigs move constantly; at force 6, cycling into the wind becomes hard work; from force 9 upward, conditions are widely described as a storm. Because it's based on observable effects, it was originally designed so sailors could estimate wind conditions without any instruments at all. The scale was formally adopted by the Royal Navy in 1838 and has since been extended and adapted for use on land as well as at sea, with each level tied to visible effects like smoke drift, moving leaves, swaying branches or, at the very top, widespread structural damage. Its enduring appeal is that anyone can estimate the local wind force just by watching how the world around them is moving, without needing to read an instrument at all.

Converting Beaufort to wind speed

Force 3 corresponds to roughly 12–19 km/h (7–12 mph), force 6 to about 39–49 km/h (24–31 mph), and force 9 to around 75–88 km/h (47–55 mph). Knowing this range is useful when you're planning a bike ride, a sail, or a day outdoors, since it translates a wind speed reading into something closer to a felt experience. Force 4 to 5, covering roughly 20–38 km/h (13–24 mph), is probably the range most people experience most often day to day: loose paper and small branches move, and light dust or spray can lift off water. Above force 10, sustained wind exceeds around 100 km/h, a level rarely reached outside severe storms, hurricanes or particularly exposed coastal and mountain locations.

What this means for your day

From around force 5 to 6, cycling — especially into the wind — starts to feel noticeably harder, and loose items like umbrellas or garden furniture can become unpredictable. At force 7 and above, take extra care near open water, on bridges, or under trees, where falling branches become a real risk. Forecasts that mention wind gusts separately from sustained wind are worth reading closely too, since gusts can briefly push conditions up several Beaufort levels. On open water, at exposed coastlines or up in the mountains, the same Beaufort number can feel considerably stronger than in a sheltered city street, since there's nothing nearby to slow the wind down before it reaches you. If a forecast for your area mentions a notably higher wind force for the coast or higher ground than for the town centre, it's worth taking that difference seriously if your plans take you there.

Why the scale still matters today

Even with precise digital wind speed readings now available everywhere, Beaufort numbers remain common in marine and aviation forecasts because they communicate impact, not just a figure. A sailor or forecaster hearing 'force 8' immediately pictures gale conditions, in a way that '65 km/h' doesn't automatically convey to most people. That's also why weather apps, including this one, often show both the number and a Beaufort-style descriptor together. Marine forecasts in particular still lean heavily on Beaufort numbers rather than raw wind speed, because sailors need an instant, intuitive sense of sea state and handling difficulty, and the scale was originally built around exactly that. Even outside sailing, keeping half an eye on the Beaufort number alongside the temperature can make a forecast far easier to picture at a glance, rather than mentally converting a km/h or mph figure every time.

Frequently asked questions

What counts as a "normal" wind speed?
Force 3 to 4 is common in most coastal and temperate regions. Force 7 or higher is less frequent and is usually called out separately in forecasts.

Why does the same wind speed feel different in different places?
Open, flat terrain, nearby water, and the direction of the wind all change how strong it feels. A gust that's barely noticeable in a sheltered city street can feel much stronger crossing an open bridge or beach.

Does the Beaufort scale account for gusts?
Not directly — it's traditionally based on sustained wind. Gusts are usually reported separately in a forecast and can briefly push conditions several Beaufort levels above the sustained reading, so it's worth checking both figures before heading into exposed conditions.

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