Specifications and equivalent speeds

Beaufort wind scale	Mean Wind Speed		Limits of wind speed		Wind descriptive terms	Probable wave height in metres*	Probable maximum wave height in metres*	Seastate	Sea descriptive terms
	Knots	m/s	Knots	m/s
0	0	0	<1	0–0.2	Calm	-	-	0	Calm (glassy)
1	2	0.8	1–3	0.3–1.5	Light air	0.1	0.1	1	Calm (rippled)
2	5	2.4	4–6	1.6–3.3	Light breeze	0.2	0.3	2	Smooth (wavelets)
3	9	4.3	7–10	3.4–5.4	Gentle breeze	0.6	1.0	3	Slight
4	13	6.7	11–16	5.5–7.9	Moderate breeze	1.0	1.5	3–4	Slight–Moderate
5	19	9.3	17–21	8.0–10.7	Fresh breeze	2.0	2.5	4	Moderate
6	24	12.3	22–27	10.8–13.8	Strong breeze	3.0	4.0	5	Rough
7	30	15.5	28–33	13.9–17.1	Near gale	4.0	5.5	5–6	Rough–Very rough
8	37	18.9	34–40	17.2–20.7	Gale	5.5	7.5	6–7	Very rough–High
9	44	22.6	41–47	20.8–24.4	Severe gale	7.0	10.0	7	High
10	52	26.4	48–55	24.5–28.4	Storm	9.0	12.5	8	Very High
11	60	30.5	56–63	28.5–32.6	Violent storm	11.5	16.0	8	Very High
12	-	-	64+	32.7+	Hurricane	14+	-	9	Phenomenal

*

1. These values refer to well-developed wind waves of the open sea.
2. The lag effect between the wind getting up and the sea increasing should be borne in mind.