Weather services issue a gale warning for maritime locations currently or imminently experiencing winds of gale force on the Beaufort scale. Gale warnings (and gale watches) allow mariners to take precautionary actions to ensure their safety at sea or to seek safe anchorage and ride out the storm on land. Though usually associated with deep low-pressure areas, winds strong enough to catalyze a gale warning can occur in other conditions too, including from anticyclones, or high-pressure systems, in the continental interior.
In the United States, the National Weather Service issues gale warnings for marine areas (oceans, sounds, estuaries, and the Great Lakes) experiencing, or about to experience, winds within the range of 34 knots (63 km/h; 39 mph) to 47 knots (87 km/h; 54 mph). In United States maritime warning flag systems, two red pennants indicate a gale warning; the use of one such flag denotes a small craft advisory.
The National Weather Service issues a storm warning for higher winds of 48 knots (89 km/h; 55 mph) to 63 knots (117 km/h; 72 mph) at sea. In the event of a tropical cyclone, however, a tropical storm warning replaces the gale warning or storm warning. The storm-warning maritime flag also replaces the gale-warning flag, regardless of the strength or weakness of the tropical storm.
The National Weather Service issues a similar high wind warning (Specific Area Message Encoding code: HWW) for high winds on land. The criteria vary from place to place; however, in most cases, the warning applies to winds of 40 miles per hour (64 km/h) to 57 miles per hour (92 km/h) for at least 1 hour; or any gusts of 58 miles per hour (93 km/h) to 73 miles per hour (117 km/h) on land unless a tropical storm warning, blizzard warning, winter storm warning, severe thunderstorm warning, or dust storm warning covers the phenomenon.
In the United Kingdom, the Meteorological Office issues gale warnings, and radio broadcasts them four times a day at fixed times on 198 kHz in the Shipping Forecast, part of the broadcast output of BBC Radio 4. If a considerable time will intervene before the next Shipping Forecast, forecasters may issue an extra gale warning, read between programmes. The Meteorological Office issues warnings for sea areas surrounding the United Kingdom for all predictions of winds of Beaufort scale Force 8 or greater, the forecasts extending as far north as Iceland and as far south as southern Spain.
Met Éireann, the Republic of Ireland meteorological office, issues an area forecast for the Irish Sea and warnings for sea areas around Ireland with headlands of Ireland (e.g. Fair Head, Malin Head, Mizen Head, Carnsore Point) defining stretches of coast.
Example of Gale Warning
399 WHUS72 KMFL 120829 MWWMFL URGENT - MARINE WEATHER MESSAGE NATIONAL WEATHER SERVICE MIAMI FL 329 AM EST FRI FEB 12 2010 ...GALE FORCE WIND GUSTS TODAY THROUGH TONIGHT... AMZ610-630-650-651-670-671-GMZ656-657-676-131200- /O.UPG.KMFL.GL.A.0001.100212T1500Z-100213T0900Z/ /O.NEW.KMFL.GL.W.0001.100212T1800Z-100213T1200Z/ LAKE OKEECHOBEE-BISCAYNE BAY- COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM- COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM- WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM- WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE BAHAMAS- COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM- COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM- GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM 20 TO 60 NM- 329 AM EST FRI FEB 12 2010 ...GALE WARNING IN EFFECT FROM 1 PM THIS AFTERNOON TO 7 AM EST SATURDAY... THE NATIONAL WEATHER SERVICE IN MIAMI HAS ISSUED A GALE WARNING... WHICH IS IN EFFECT FROM 1 PM THIS AFTERNOON TO 7 AM EST SATURDAY. THE GALE WATCH IS NO LONGER IN EFFECT. A STRONG LOW PRESSURE SYSTEM WILL PASS NORTH OF THE REGION THIS EVENING. STRONG SOUTHERLY WINDS ARE EXPECTED TO DEVELOP QUICKLY TODAY AHEAD OF THE LOW...WITH STRONG WESTERLY WINDS BEHIND THE ASSOCIATED COLD FRONT PASSING DURING THE EVENING HOURS. SUSTAINED WINDS OF 25 TO 30 KNOTS ARE POSSIBLE WITH FREQUENT GUSTS TO NEAR 40 KNOTS EVEN OUTSIDE OF THUNDERSTORMS. THESE WINDS WILL LEAD TO EXTREMELY DANGEROUS MARINE CONDITIONS. PRECAUTIONARY/PREPAREDNESS ACTIONS... A GALE WARNING MEANS WINDS OF 34 TO 47 KNOTS ARE IMMINENT OR OCCURRING. OPERATING A VESSEL IN GALE CONDITIONS REQUIRES EXPERIENCE AND PROPERLY EQUIPPED VESSELS. IT IS HIGHLY RECOMMENDED THAT MARINERS WITHOUT THE PROPER EXPERIENCE SEEK SAFE HARBOR PRIOR TO THE ONSET OF GALE CONDITIONS.