Echelle BEAUFORT scale / Skala

The Beaufort Scale, as originally drawn up, made no reference to the speed of the wind and various attempts have been made to correlate the two.

Specially when sailing in high latitudes, wind gains additional strength due to cold and related higher air density. Also the effect of windchill on bare skin make cold water sailing more dangerous.

Information on related windchill.

Conversion table
Table de conversion
Umrechnungstafel

Wind Force / force vent (Bft):
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

Wind speed / vitesse vent (kts):
0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70

Wind speed / vitesse vent (km/h):
0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120

Sea Disturbance Number / état de la mer:
0, 1, 2, 3, 4, 5, 6, 7, 8, 9

Average wave height / hauteur de vague (m):
0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16

Average wave height / hauteur de vague (ft):
0, 1, 2, 4, 10, 15, 20, 25, 30, 35, 40, 45, 50

0 Bft

Calm
Calme
Winstille

Wind speeds:
less than 1 knot (<1 mph; <1 kph; <0.3 m/s)

At sea:

Sea like a mirror, calm

La fumée s'élève verticalement ; la mer est comme un miroir

Spiegelglatte See

Sea disturbance number: 0

Probable wave height: flat (0 ft; 0 m)

On land: Smoke rises vertically

Notes: Boring, boring, boring...

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

1 Bft

Light Air
Très légère brise
Leiser Zug

Wind speeds:
1-3 knots (1-3 mph; 1-5 kph; 0.3-1.5 m/s)

At sea:

Ripples with the appearance of scales are formed but without foam crests

Il se forme des rides, mais il n'y a pas d'écume

Kleine schuppenförmig aussehende Kräuselwellen ohne Schaumkämme

Sea disturbance number: 0

Probable wave height: 5-10 cm (2-4 in) (0 ft; 0 m)

On land: Direction of wind shown by smoke drift, but not by vanes

Notes: Yachts just have steerage way

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

2 Bft

Light Breeze
Légère brise
Leichte Brise

Wind speeds:
4-6 knots (4-7 mph; 6-11 kph; 1.6-3.3 m/s)

At sea:

Small wavelets, still short but more pronounced; crests have a glassy appearance and do not break

Vaguelettes courtes ; leurs crêtes ne déferlent pas

Kleine Wellen, noch kurz, aber ausgeprägter. Die Kämme sehen
glasig aus und brechen sich nicht

Sea disturbance number: 1

Probable wave height: 10-15 cm (4-6 in); (0-1 ft; 0-0.3 m)

On land: Wind felt on face; leaves rustle; ordinary vane moved by wind

Notes: Wind fills sails of yacht, which then may move at 1-2 knots

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

3 Bft

Gentle Breeze
Petite brise
Schwache Brise

Wind speeds:
7-10 knots (8-12 mph; 12-19 kph; 3.4-5.4 m/s)

At sea:

Large wavelets; crests begin to break; foam of glassy appearance; perhaps scattered white horses

Très petites vagues ; écume d'aspect vitreux

Die Kämme beginnen sich zu brechen. Schaum überwiegend glasig, ganz vereinzelt können weisse Schaumköpfe auftreten

Sea disturbance number: 2

Probable wave height: 60 cm (2 ft); (1-2 ft; 0.3-0.6 m)

On land: Leaves and small twigs in constant motion; wind extends light flag

Notes: Yachts start to careen and travel at 3-4 knots

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

4 Bft

Moderate Breeze
Jolie brise
Mässige Brise

Wind speeds:
11-16 knots (13-18 mph; 20-28 kph; 5.5-7.9 m/s)

At sea:

Small waves, becoming longer; fairly frequent white horses

Petites vagues devenant plus longues ; moutons nombreux

Wellen sind noch klein, werden aber länger. Weisse Schaumköpfe treten schon ziemlich verbreitet auf

Sea disturbance number: 3

Probable wave height: 1 m (3.5 ft); (2-4 ft; 0.6-1.2 m)

On land: Raises dust and loose paper; small branches are moved

Notes: Good working breeze for yachts; carry all sail with good list

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

5 Bft

Fresh Breeze
Bonne brise
Frische Bise

Wind speeds:
17-21 knots (19-24 mph; 29-38 kph; 8.0-10.7 m/s)

At sea:

Moderate waves taking a more pronounced long form; many white hourses are formed; chance of some spray

Vagues modérées, allongées ; moutons nombreux

Mässige Wellen, die eine ausgeprägtere lange Form annehmen. Überall weisse Schaumkämme. Ganz vereinzelt kann schon Gischt vorkommen

Sea disturbance number: 4

Probable wave height: 2 m (6-7 ft); (4-8 ft; 1.2-2.4 m)

On land: Small trees in leaf begin to sway; crested wavelets form on inland waters

Notes: Yachts shorten sail

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

6 Bft

Strong Breeze
Vent frais
Starker Wind

Wind speeds:
22-27 knots (25-31 mph; 39-49 kph; 10.8-13.8 m/s)

At sea:

Large waves begin to form; the white foan crests are more extensive everywhere; probably some spray

Des lames se forment ; crêtes d'écume blanche plus étendues

Die Bildung grosser Wellen beginnt; Kämme brechen und hinterlassen grössere weisse Schaumflächen; etwas Gischt

Sea disturbance number: 5

Probable wave height: 3 m (9-10 ft); (8-13 ft; 2.4-4 m)

On land: Large branches in motion; whistling heard in telegraph wires; umbrellas used with dificulty

Notes: Yachts with double reef in mainsail; cared required when fishing

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

7 Bft

Near Gale / Moderate Gale
Grand frais
Steifer Wind

Wind speeds:
28-33 knots (32-38 mph; 50-61 kph; 13.9-17.1 m/s)

At sea:

Sea heaps up and white foam from the breaking waves begins to be blown in streaks along the direction of the wind

La mer grossit ; l'écume est soufflée en trainées ; lames déferlantes

See türmt sich; der beim Brechen entstehende weisse Schaum beginnt sich in die Windrichtung zu legen

Sea disturbance number: 6

Probable wave height: 4 m (13-14 ft); (13-20 ft; 4-6 m)

On land: Whole trees in motion; inconvenience felt when walking against wind

Notes: Yachts remain in harbour, those at sea lie to

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

8 Bft

Gale / Fresh Gale
Coup de vent
Stürmischer Wind

Wind speeds:
34-40 knots (39-46 mph; 62-74 kph; 17.2-20.7 m/s)

At sea:

Moderately high waves of greater length; edges crests begin to break into spindrift; the foam is blown in well-marked streaks along the direction of the wind

Lames de hauteur moyenne ; de leurs crêtes se détachent des tourbillons d'embruns

Mässig hohe Wellenberge mit Kämmen von beträchtlicher Länge. Von den Kanten der Kämme beginnt Gischt abzuwehen. Der Schaum legt sich in gut ausgeprägten Streifen in die Windrichtung

Sea disturbance number: 6

Probable wave height: 5.5 m (18 ft); (13-20 ft; 4-6 m)

On land: Breaks twigs off trees; generally impedes progress

Notes: All yachts make for harbour if possible

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

9 Bft

Strong Gale
Fort coup de vent
Sturm

Wind speeds:
41-47 knots (47-54 mph; 75-88 kph; 20.8-24.4 m/s)

At sea:

High waves; dense streaks of foam along the direction of wind; crests of waves begin to topple, tumble and roll over; spray may affect visibility

grosses lames ; leur crête s'écroule et déferle en rouleaux

Hohe Wellenberge; Dichte Schaumstreifen in Windrichtung; "Rollen" der See beginnt. Der Gischt kann die Sicht schon beeinträchtigen

Sea disturbance number: 6

Probable wave height: 7 m (23 ft); (13-20 ft; 4-6 m)

On land: Slight structural damage occurs (chimney post and slates removed)

Notes:

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

10 Bft

Whole Gale / Storm
Tempête
Schwerer Sturm

Wind speeds:
48-55 knots (55-63 mph; 89-102 kph; 24.5-28.4 m/s)

At sea:

Very high waves with long overhanging crests; resulting foam in great patches is blown in dense white streaks along the direction of the wind; on the whole, the surface of the sea takes a white appearance; tumbling of the sea becomes heavy and shock-like; visibility affected

Très grosses lames à longues crêtes en panache ; déferlement en rouleaux intense et brutal

Sehr hohe Wellenberge mit langen überbrechenden Kämmen. See weiss durch Schaum. Rollen der See schwer und stossartig. Sicht durch Gischt beeinträchtigt

Sea disturbance number: 7

Probable wave height: 9 m (29 ft); (20-30 ft; 6-9 m)

On land: Seldom experienced inland; trees uprooted; considerable structural damage occurs

Notes:

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

11 Bft

Storm / Violent storm
Violente tempête
Orkanartiger Sturm

Wind speeds:
56-63 knots (64-75 mph; 103-117 kph; 28.5-32.6 m/s)

At sea:

Exceptionally high waves (small and medium size ships might be for a time lost from view behind waves); sea is completely covered with long white patches of foam lying along the direction of wind; everywhere the edges are blown into froth; visibility afected

Lames exceptionnellement hautes ; mer recouverte de bancs d'écume blanche

Aussergewöhnlich hohe Wellenberge. Die Kanten der Wellenkämme werden überall zu Gischt zerblasen. Die Sicht ist herabgesetzt

Sea disturbance number: 8

Probable wave height: 11 m (37 ft); (30-45 ft; 9-14 m)

On land: Very rarely experienced; accompanied by widespread damage

Notes:

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+

12-17 Bft

Hurricane
Ouragan
Orkan

Wind speeds:
64 knots and greater (> 75 mph; >117 kph; >32.7 m/s)

At sea:

The air is filled with foam and spray; sea completely white with driving spray; visibility very seriously affected

Air plein d'écume et d'embruns ; mer entièrement blanche ; visibilité très réduite

Luft mit Schaum und Gischt angefüllt. See vollständig weiss. Die Sicht ist sehr stark herabgesetzt; jede Fernsicht hört auf

Sea disturbance number: 9

Probable wave height: 11 m and more (> 37 ft); (>45 ft; >14 m)

On land: Very rarely experienced; accompanied by widespread damage

Notes:
13 Bft > 72-80 kts
14 Bft > 81-89 kts
15 Bft > 90-99 kts
16 Bft > 100- 108 kts
17 Bft > 109- 118 kts

Go to Beaufort number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12+