What Is A Small Craft Advisory And How To Prepare

The National Oceanic and Atmospheric Administration (NOAA) offers a number of resources to help mariners navigate safely during severe weather events.

One such tool is the Small Craft Advisory, which warns boaters of dangerous weather conditions affecting coastal waters. 

What Is A Small Craft Advisory And How To Prepare

This advisory is typically displayed on weather radio stations, though it can also be seen at some small boat stations along the coast.

Small craft advisories alert boaters to hazardous marine conditions, including rough seas, high winds, heavy rain, foggy conditions, low visibility, and snow.

If you see one of these signs, take note and avoid traveling near the coast.

Flags and colored lights used to signal a Small Craft Advisory include:

  • Red – Strong wind warning
  • Orange – High surf warning
  • Yellow – Heavy rain warning
  • Green – Fog warning
  • White – Low visibility warning
  • Blue – Snow warning

Action Required 

A Small Craft Advisory is issued when continuous wind speeds that dictate the issuing of a Small Craft Advisory reach dangerous levels.

These wind speed thresholds vary based on the geographical area but are generally between 30 and 35 knots.

This advisory is meant to warn mariners about unsafe weather conditions and give them information on how to prepare for those conditions.

All boaters should take appropriate precautions during a Small Craft Advisory, including checking local forecasts and taking necessary safety measures before heading out into the water.

Boats should avoid traveling near other vessels and shorelines, and should anchor well away from bridges and piers.

Boaters should also ensure that life jackets, flares, emergency radio equipment, and navigation lights are readily accessible.

Boat Size

The National Weather Service defines small craft advisory as “a marine weather statement intended primarily for mariners operating vessels less than 24 feet in length.”

A small craft advisory is issued when there is a threat of conditions that could cause damage to boats under 24 feet in length.

A small craft advisory is defined as a general warning of poor visibility due to fog or rain.

This advisory is typically issued during periods of low pressure over water where winds are light and/or seas are calm. These advisories are usually limited to areas within 40 miles of land.

When issuing a small craft advisory, the NWS states that it is important to keep track of the weather forecast for your area.

If you plan to operate your vessel outside of the recommended area, make sure that you check the latest forecasts.

Hurricane Warning 

Hurricane Warning 

The National Weather Service issues hurricane watches and warnings to alert residents about possible impacts from dangerous weather conditions.

A watch means that hurricane conditions are possible within 36 hours and are imminent.

A hurricane watch area is defined as being under hurricane force winds. These areas include coastal waters from Cape Hatteras, North Carolina, southward to the Texas/Mexico Border.

If you live in one of these areas, it’s important to monitor local media outlets and follow instructions from local officials.

You can visit NOAA’s Hurricane Center for up-to-date information on current tropical cyclones.

Warning Explanations 

The threshold for issuing an advisory depends on the area covered.

For example, an advisory is issued when there is a significant risk of encountering dangerous waves or currents. In general, the following criteria must be met for an advisory to be issued:

  1. Sea or lake ice must exist;
  2. Wind speeds greater than 15 knots (19 km/h);
  3. Wave heights greater than 3 feet (0.9 m) above normal spring tides;
  4. Currents stronger than 2 knots (3 km/h).

In addition, an advisory may be issued when there is a threat of severe winds or rough seas.

Other Types Of Warnings 

Other types of weather warnings can include:

  • Gale Warning: A warning has been issued for sustained wind speeds of 34 knots to 47 knots (39 to 54 mph). gale force winds are forecasted.
  • Storm Warning: A warning has been posted for sustained winds of 48 knots to 55 knots (54 to 65 mph) and/or frequent gusts up to 72 knots (77 mph). Storm Warnings cover a smaller region than a Storm Watch.
  • Tropical Storm Warning: A warning has now been issued for sustained winds of 39 to 73 knots (39 to 73 mph), or frequent gusts of 64 knots (74mph) or greater. Tropical Storm Warnings cover a larger region than a Storm Watch but are smaller than a Hurricane Warning.
  • Hurricane Warning: This is the highest level of alert for a hurricane. Sustained winds of 74 knots (79 mph) or greater are expected within 24 hours. These warnings cover a much larger area than a Tropical Storm Warning.
  • Hurricane Watch: A watch has been issued for a hurricane. Slight strengthening is possible during the next 48 hours.
  • Tropical Storm Warning (TSW): A TSW watches the potential development of a tropical depression into a tropical storm. If a tropical storm forms, it could become a hurricane.

Coastal Display Warnings/Summary

As mentioned earlier the National Weather Service is encouraging local governments along the coast to adopt a program called the Coastal Warning Display System.

This system allows coastal communities to communicate weather information to boaters, fishermen, and others who frequent the water. 

The Coastal Warning Display System consists of a set of flags, each measuring 8 feet long and 4 inches wide. Each flag represents one of the different weather hazards:

  • Fog
  • High Surf
  • Large Waves
  • Small Craft Advisory
  • Storm Surge
  • Strong Winds
  • Swell
  • Water Spout
  • Whitecaps

Each flag should be displayed at intervals of 1 mile along the shoreline. Flags should be flown from high tide to low tide.

Flag colors indicate the severity of the hazard, with red being the most serious and green the being least serious.


Sea conditions can change very quickly so it’s important to understand the warnings issued in order to deal safely with erratic weather conditions.

This information on small craft advisories will help boaters stay safe at sea. Want to know more about a small craft advisory? Check out this video from Wayne The Boat Guy.

Andrew Capper