The Beaufort Scale

Force 0: Calm

Sea: Flat.

Land: Calm. Smoke rises vertically.


1: Light air

Ripples without crests.

Wind motion visible in smoke.


2 Light breeze

Small wavelets. Crests of glassy appearance, not breaking

Wind felt on exposed skin. Leaves rustle.


3 Gentle breeze

Large wavelets. Crests begin to break; scattered whitecaps

Leaves and smaller twigs in constant motion.


4 Moderate breeze

Small waves with breaking crests. Fairly frequent white horses.

Dust and loose paper raised. Small branches begin to move.


5 Fresh breeze

Moderate waves of some length. Many white horses. Small amounts of spray.

Branches of a moderate size move. Small trees begin to sway.


6 Strong breeze

Long waves begin to form. White foam crests are very frequent. Some airborne spray is present.

Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. Empty plastic garbage cans tip over.


7 High wind, Moderate gale, Near gale

Sea heaps up. Some foam from breaking waves is blown into streaks along wind direction. Moderate amounts of airborne spray.

Whole trees in motion. Effort needed to walk against the wind. Swaying of skyscrapers may be felt, especially by people on upper floors.


8 Gale, Fresh gale

Moderately high waves with breaking crests forming spindrift. Well-marked streaks of foam are blown along wind direction. Considerable airborne spray.

Some twigs broken from trees. Cars veer on road. Progress on foot is seriously impeded.


9 Strong gale

High waves whose crests sometimes roll over. Dense foam is blown along wind direction. Large amounts of airborne spray may begin to reduce visibility.

Some branches break off trees, and some small trees blow over. Construction/temporary signs and barricades blow over. Damage to circus tents and canopies.


10 Storm, Whole gale

Very high waves with overhanging crests. Large patches of foam from wave crests give the sea a white appearance. Considerable tumbling of waves with heavy impact. Large amounts of airborne spray reduce visibility.

Trees are broken off or uprooted, saplings bent and deformed. Poorly attached asphalt shingles and shingles in poor condition peel off roofs.


11 Violent storm

Exceptionally high waves. Very large patches of foam, driven before the wind, cover much of the sea surface. Very large amounts of airborne spray severely reduce visibility.

Widespread vegetation damage. Many roofing surfaces are damaged; asphalt tiles that have curled up and/or fractured due to age may break away completely.


12 Hurricane

Huge waves. Sea is completely white with foam and spray. Air is filled with driving spray, greatly reducing visibility.

Very widespread damage to vegetation. Some windows may break; mobile homes and poorly constructed sheds and barns are damaged. Debris may be hurled about.