Weather Definitions

The National Weather Service has an ascending series of alerting messages, or advisories and warnings, for mariners. These are keyed to increasingly hazardous weather and sea conditions.

Each advisory or warning condition has both a day and a night signal, which are displayed at prominent locations ashore such as a Coast Guard station, lighthouse, yacht clubs, and marinas. Some locations will display only the day signal, others will display both day and night signals. Day signals only are flown from Coast Guard lightships while on station.

IMPORTANT: Visual signals are supplementary to, and should not be considered replacements for, written advisories and warnings broadcasts by the press, radio, and television.

Small Craft Advisory

Condition: Winds up to 33 knots (38 miles per hour)
Visual Signal: One red pennant displayed by day and a red light above a white light at night

Gale Warning

Condition: Winds ranging from 34 to 47 knots (39 to 54 miles per hour)
Visual Signal: Two red pennants displayed by day and a white light above a red light at night

Storm Warning

Condition: Winds from 48 knots (55 miles per hour) and above, no matter how high the velocity!
NOTE: If winds are associated with a tropical cyclone (hurricane), the storm warning display indicates forecast winds of 48 to 63 knots (55 to 73 miles per hour). The hurricane warning is displayed only in connection with a tropical cyclone (hurricane).
Visual Signal: A single square red flag with a black center displayed by day and two red lights at night

Hurricane Warning

Condition: Winds from 64 knots (74 miles per hour) and above
Visual Signal: Two square red flags with black centers displayed by day and a white light between two red lights at night