Beaufort number	Wind speed (km/h)	Description	Wave height (meters)	Sea conditions	Land conditions
0	0	Calm	0	Flat.	Calm. Smoke rises vertically.
1	1-6	Light air	0.1	Ripples without crests.	Wind motion visible in smoke.
2	7-11	Light breeze	0.2	Small wavelets. Crests of glassy appearance, not breaking	Wind felt on exposed skin. Leaves rustle.
3	12-19	Gentle breeze	0.6	Large wavelets. Crests begin to break; scattered whitecaps	Leaves and smaller twigs in constant motion.
4	20-29	Moderate breeze	1	Small waves.	Dust and loose paper raised. Small branches begin to move.
5	30-39	Fresh breeze	2	Moderate (1.2 m) longer waves. Some foam and spray.	Smaller trees sway.
6	40-50	Strong breeze	3	Large waves with foam crests and some spray.	Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult.
7	51-62	Near gale	4	Sea heaps up and foam begins to streak.	Whole trees in motion. Effort needed to walk against the wind.
8	63-75	Gale	5.5	Moderately high waves with breaking crests forming spindrift. Streaks of foam.	Twigs broken from trees. Cars veer on road.
9	76-87	Strong gale	7	High waves (2.75 m) with dense foam. Wave crests start to roll over. Considerable spray.	Light structure damage.
10	88-102	Storm	9	Very high waves. The sea surface is white and there is considerable tumbling. Visibility is reduced.	Trees uprooted. Considerable structural damage.
11	103-119	Violent storm	11.5	Exceptionally high waves.	Widespread structural damage.
12	120	Hurricane	14+	Huge waves. Air filled with foam and spray. Sea completely white with driving spray. Visibility greatly reduced.	Considerable and widespread damage to structures.