Marine forecasts glossary

Marine forecasts contain a number of terms which are used to convey specific meanings.

Gale warnings


Winds of at least Beaufort force 8 (34-40 knots) or gusts reaching 43-51 knots

Severe gale

Winds of force 9 (41-47 knots) or gusts reaching 52-60 knots


Winds of force 10 (48-55 knots) or gusts reaching 61-68 knots

Violent storm

Winds of force 11 (56-63 knots) or gusts of 69 knots or more

Hurricane force

Winds of force 12 (64 knots or more)

Note: The term used is 'hurricane force'; the term 'hurricane' on its own means a true tropical cyclone, not experienced in British waters.


Expected within six hours of time of issue


Expected within six to 12 hours of time of issue


Expected more than 12 hours from time of issue


Very poor

Visibility less than 1,000 metres


Visibility between 1,000 metres and 2 nautical miles


Visibility between 2 and 5 nautical miles


Visibility more than 5 nautical miles

Movement of pressure systems


Moving at less than 15 knots


Moving at 15 to 25 knots

Rather quickly

Moving at 25 to 35 knots


Moving at 35 to 45 knots

Very rapidly

Moving at more than 45 knots

Pressure tendency in station reports

Rising (or falling) more slowly

Pressure rising (or falling) at a progressively slower rate through the preceding three hours

Rising (or falling) slowly

Pressure change of 0.1 to 1.5 hPa in the preceding three hours

Rising (or falling)

Pressure change of 1.6 to 3.5 hPa in the preceding three hours

Rising (or falling) quickly

Pressure change of 3.6 to 6.0 hPa in the preceding three hours

Rising (or falling) v. rapidly

Pressure change of more than 6.0 hPa in the preceding three hours

Now rising (or falling)

Pressure has been falling (rising) or steady in the preceding three hours, but at the time of observation was definitely rising (falling)

Note: For those more familiar with the millibar, 1 hPa = 1 mb


Wind direction

Indicates the direction from which the wind is blowing

Becoming cyclonic

Indicates that there will be considerable change in wind direction across the path of a depression within the forecast area


The changing of the wind direction clockwise, e.g. SW to W


The changing of the wind in the opposite direction to veering (anticlockwise), e.g. SE to NE

Sea state


Wave height less than 0.5 m


Wave height of 0.5 to 1.25 m


Wave height of 1.25 to 2.5 m


Wave height of 2.5 to 4.0 m

Very rough

Wave height of 4.0 to 6.0 m


Wave height of 6.0 to 9.0 m

Very high

Wave height of 9.0 to 14.0 m


Wave height more than 14.0 m

Last updated: 26 February 2013