These charts are for guidance only, actually gusts and wave heights may be considerably higher than those shown.|
The wind barbs indicate the forecast medium wind speed and wind direction at 10 meters above ground level. Wind speed is indicated here by the number and length of wind barbs, each short barb representing 5 knots, each long barb 10 knots (see table Wind Barb Scale below).
Information about the corresponding wind speeds and sea criteria is posted in the below Beaufort Wind Scale.
Wind speed and wind direction information are expected average values for the surrounding surface. Due to small scale effects (topography, air/sea, etc.) there may be local variations. For a given wind force, sea conditions can be more dangerous near land than in the open waters. In many tidal waters wave heights are liable to increase considerably in a matter of minutes. The Beaufort values displayed in the wind charts are not representing absolute peak gusts, which can easily exceed twice the speed. The Beaufort values displayed in the wind- and the peak gusts charts are not maximal values, but values averaged over a 10 minute period.
|Force number||Wind speed||Description|
|Sea criteria||Land criteria|
|0||<1||0-0.2||<1||<1||Calm||Sea like a mirror.||Smoke rises vertically.|
|1||1-3||0.3-1.5||1-5||1-3||Light air||Ripples with the appearance of scales are formed but without foam crests.||Direction of wind shown by smoke but not by wind vanes.|
|2||4-6||1.6-3.3||6-11||4-7||Light breeze||Small wavelets, still short but more pronounced. Crests have a glassy appearance and do not break||Wind felt on face; leaves rustle; ordinary vane moved by wind.|
|3||7-10||3.4-5.4||12-19||8-12||Gentle breeze||Large wavelets. Crests begin to break. Foam of glassy appearance. Perhaps scattered white horses.||Leaves and small twigs in constant motion; wind extends light flag.|
|4||11-16||5.5-7.9||20-28||13-18||Moderate breeze||Small waves, becoming longer; fairly frequent horses.||Raises dust and loose paper; small branches are moved.|
|5||17-21||8.0-10.7||29-38||19-24||Fresh breeze||Moderate waves, taking a more pronounced long form; many white horses are formed. (Chance of some spray.)||Small trees in leaf begin to sway; wavelets form on inland waters.|
|6||22-27||10.8-13.8||39-49||25-31||Strong breeze||Large waves begin to form; the white foam crests are more extensive everywhere. (Probably some spray.)||Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty.|
|7||28-33||13.9-17.1||50-61||32-38||Near gale||Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind.||Whole trees in motion; inconvenience felt when walking against the wind; umbrellas discarded in exposed places.|
|8||34-40||17.2-20.7||62-74||39-46||Gale||Moderately high waves of greater length; edges of crests begin to break into spindrift. The foam is blown in well-marked streaks along the direction of the wind.||Some twigs broken from trees. Cars veer on road. Progress on foot is seriously impeded.|
|9||41-47||20.8-24.4||75-88||47-54||Strong gale||High waves. Dense streaks of foam along the direction of the wind. Crests of waves begin to topple, tumble, and roll over. Spray may affect visibility.||Slight structural damage occurs (chimney-pots and slates removed).|
|10||48-55||24.5-28.4||89-102||55-63||Storm||Very high waves with long overhanging crests. The 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. The tumbling of the sea becomes heavy and shocklike. Visibility affected.||Seldom experienced inland; trees uprooted; considerable structural damage occurs.|
|11||56-63||28.5-32.6||103-117||64-72||Violent storm||Exceptionally high waves. (Small and medium-sized ships might be for a time lost to view behind the waves.) The sea is completely covered with long white patches of foam lying along the direction of the wind. Everywhere the edges of the wave crests are blown into froth. Visibility affected.||Very rarely experienced; accompanied by widespread damage.|
|12||64 +||32.7-36.9||>118||73-82||Hurricane||The air is filled with foam and spray. Sea completely white with driving spray; visibility very seriously affected.||Countryside is devastated.|