Marine Forecast by ZIP Code
Enter a US ZIP code for the National Weather Service forecast for the nearest coastal waters, with any small craft advisories, gale warnings and other marine alerts in effect.
How it works
The National Weather Service splits US coastal waters, bays, sounds and the Great Lakes into marine forecast zones. This tool finds the zones closest to your ZIP code, then loads the latest zone forecast and any active alerts straight from the NWS. Marine zones cover water only, so a ZIP code on land is matched to the nearest zone boundary. Use the buttons above the forecast to switch between a bay, a sound and the open coast.
Coastal waters forecasts usually reach 20 nautical miles out, and offshore forecasts cover the water beyond. If you are heading 15 miles out, weight the coastal forecast most heavily: our 3 to 5 foot seas guide suggests a blend of about 80 percent coastal and 20 percent offshore.
Marine alerts at a glance
| Alert | What it means |
|---|---|
| Small Craft Advisory | Winds or seas hazardous to small boats. The trigger is set locally, usually winds from the low 20s to 33 knots or seas of about 5 to 7 feet. |
| Gale Warning | Sustained winds or frequent gusts of 34 to 47 knots. |
| Storm Warning | Sustained winds or frequent gusts of 48 to 63 knots. |
| Hurricane Force Wind Warning | Winds of 64 knots or more from a storm that is not a tropical cyclone. |
| Hazardous Seas Warning | Waves high or steep enough to endanger all vessels, without gale-force wind. |
| Special Marine Warning | A short-lived hazard, such as thunderstorm winds of 34 knots or more or a waterspout, usually for under two hours. |
| Dense Fog Advisory | Visibility over the water of 1 nautical mile or less. |
Watches mean the hazard is possible, usually within 48 hours. Warnings and advisories mean it is expected or happening.
Reading the forecast
Winds are in knots and seas in feet. "Seas 3 to 5 ft" is the significant wave height, the average of the highest third of the waves, so expect the odd wave near twice that. The wave detail line lists each set of waves with its direction, height and period, for example "SE 3 ft at 6 seconds". Tap "Decode this" on any forecast period to open it in the sea state calculator and see what it means for your boat.
Questions
Where does the marine forecast come from?
Directly from the National Weather Service at api.weather.gov. The forecast text and alerts are the same ones broadcast on NOAA Weather Radio and posted at weather.gov. Always check the issue time: forecasts are updated at least twice a day, and more often when conditions change.
Why does my ZIP code show a zone several miles away?
Marine zones cover only the water. The tool picks the zone whose edge is closest to the center of your ZIP code and lists other nearby zones as buttons, so you can switch to the bay, sound or stretch of coast you plan to use.
Does it cover lakes?
It covers the Great Lakes, which have NWS marine zones. Other lakes and rivers don't have marine forecasts, so for those check the regular NWS forecast for your town, paying attention to wind speed and gusts.
What is the difference between an advisory and a warning?
An advisory is for conditions that are hazardous mainly to small boats. A warning is for conditions dangerous to all vessels, such as a gale. A watch means those conditions are possible, usually within 48 hours.
Is my location stored?
Only in your own browser, so the tool remembers it next time. It is not sent to Lazy Seas. The coordinates of your ZIP code are sent to the National Weather Service to look up alerts for the shoreline.