The Weather Radio broadcast is the best weather-related resource for boaters. NOAA is also a great resource, as they use a Coastal Warning Display Program.
There are several types of flags and colored lights used to display warnings of incoming weather to boaters.
What Is a Small Craft Advisory?
The National Weather Service issues a Small Craft Advisory when winds have reached dangerous speeds. Generally, sustained winds between 20 and 33 knots are enough to issue a Small Craft Advisory. Other conditions, such as ice, can also trigger this warning. When these warnings are issued, all boaters should take precautions.
Small Craft Advisory: Boat Size
While the National Weather Service does not explicitly define a small craft, operator experience, vessel type and size, and water conditions should all be considered.
Small Craft Advisory: Winds of 18 to 33 knots, or 24 to 38 miles per hour.
Gale Warning: Winds of 34 to 47 knots, or 39 to 54 miles per hour.
Storm Warning: Winds greater than 48 knots, or 55 miles per hour.
Hurricane Warning: Winds greater than 64 knots, or 74 miles per hour.
Tropical Storm Warning: Winds between 34 and 64 knots that are associated with a storm system expected to last longer than two hours.
Special Marine Warning: Observed or forecast winds of 34 knots or higher, coupled with a storm expected to last more than two hours.