The Beaufort scale is an empirical measure that correlates wind speed to observed conditions at sea or on land.

Wind categoryBeaufort numberWind speedConditions
Advisory-force625–31 mph
(40–50 km/h)
Large branches in motion; whistling in telephone wires.
Advisory-force732–38 mph
(51–62 km/h)
Whole trees in motion; inconvenience felt walking against wind.
Gale-force8–939–54 mph
(63–88 km/h)
Twigs break off trees; wind generally impedes progress. Tropical storm criteria begin.
Storm-force10–1155–73 mph
(89–117 km/h)
Damage to chimneys and television antennas; pushes over shallow-rooted trees. Severe thunderstorm criteria begin (58 mph (93 km/h)).
Hurricane-force12–1374–112 mph
(118–181 km/h)
Peels shingles off roofs; windows broken if struck by debris; trees uprooted or snapped; mobile homes severely damaged or overturned; moving cars pushed off-road. Hurricane criteria begin.
Major hurricane-force
Extreme wind
14–16113–237 mph
(182–381 km/h)
Roofs torn off houses; cars lifted off ground; trees defoliated and sometimes debarked. Major hurricane criteria begin.

:Beaufort levels above 12 are non-standard in the United States. Instead, the Saffir–Simpson hurricane scale (Category 1, Category 2, etc.) is used.