National Weather Service United States Department of Commerce

The National Weather Service's Marine, Tropical, and Tsunami Services Branch (W/AFS26) is responsible for oversight of the Marine, Tropical, and Tsunami Services Programs. The programs provide current, accurate weather and water information relating to the 95,439 statute miles of shoreline mileage of the U.S., which includes the Great Lakes (Shoreline Mileage of the U.S. ) and offshore and high seas waters. This information aims to:

  • Ensure the safety of life and protection of property
  • Promote international and interstate commerce by improving the efficiency of marine operations
  • Mitigate environmental impacts
  • Enhance the quality of life for the United States

America’s marine economy, including goods and services, contributed about $373 billion to the nation’s gross domestic product in 2018 and grew faster than the nation’s economy as a whole. Marine-related gross domestic product grew 5.8% from 2017 to 2018, faster than the 5.4% growth of the total U.S. gross domestic product as measured in current dollars. Businesses also supported 2.3 million marine related jobs in 2018. 

The sectors making the largest contributions to the nation’s gross domestic product, not adjusted for inflation, are:

  • Tourism and recreation, including recreational fishing ($143 billion)

  • National defense and public administration ($124 billion)

  • Offshore minerals ($49 billion)

  • Transportation and warehousing ($25 billion)

  • Living resources, including commercial fishing and aquaculture ($13 billion)

  • Ship and boat building ($9 billion)

  • Power generation ($4 billion)

  • Research and education ($3 billion)

  • Construction ($2.5 billion)

  • Professional and technical services ($31 million)

For more information on the US marine economy, go to:

California and Florida are major contributors for the tourism and recreation sector. Combined, these states account for more than one-third of the sector's total employment and GDP. Virginia contributes the most to employment for ship and boat building, accounting for 23 percent. Washington is the largest contributor to GDP for ship and boat building, accounting for 20.7 percent. Texas is home to the national center for oil and gas industry. Harris County, Texas alone accounted for 66 percent of employment for the offshore mineral extraction sector and 80 percent of its GDP.

Death from rip currents, hurricanes and associated flooding represent a major share of U.S. weather-related fatalities. According to the CDC, commercial fishing is one of the most hazardous occupations in the United States with a fatality rate 29 times higher than the national average and severe weather conditions are the primary contributor to the fatalities.

According to the National Ocean Service, In the United States, counties directly on the shoreline constitute less than 10 percent of the total land area (not including Alaska), but account for 39 percent of the total population. From 1970 to 2010, the population of these counties increased by almost 40% and are projected to increase by an additional 10 million people or 8% by 2020. Coastal areas are substantially more crowded than the U.S. as a whole, and population density in coastal areas will continue to increase in the future. In fact, the population density of coastal shoreline counties is over six times greater than the corresponding inland counties.

Using the weather analyses and forecast guidance provided by NCEP, along with radar, satellite, and in-situ observational data, NWS marine weather forecasters issue wind, sea state, and significant weather warnings, forecasts, and weather statements.These are essential to the conduct of safe and efficient maritime operations and for the protection of the marine public.

The collection of weather observations is vital to accurate weather forecasting, and especially so over the waters where weather stations are few and far between. Thousands of vessels worldwide are Volunteer Observing Ships (VOS), sending observations every few hours which are used by marine forecasters and computer modelers to improve the accuracy of the forecasts. The National Data Buoy Center (NDBC) maintains 103 buoys and 47 fixed C-MAN stations in the oceans and the Great Lakes.

Marine forecasts are also issued as needed to aid in search and rescue operations, the containment and cleanup of oil spills or support to other disasters such as plane crash recovery operations.

The NWS operates two Tsunami Warning Centers that are staffed 24 hours a day, 7 days a week to help protect life and property from tsunamis. These centers monitor for tsunamis and the earthquakes that cause them, forecast tsunami impacts, and prepare and issue tsunami messages. The National Tsunami Warning Center in Alaska provides tsunami messages for the continental United States, Alaska and Canada. The Pacific Tsunami Warning Center in Hawaii provides tsunami messages for the Hawaiian Islands, the U.S. Pacific and Caribbean territories, and the British Virgin Islands and provides forecast information to international partners in the Pacific and Caribbean and adjacent regions to help them understand the threat to their coasts so they can decide whether or not to issue alerts. NDBC also maintains and provides data from the U.S. network of Deep-ocean Assessment and Reporting of Tsunami systems and provides data from the National Ocean Service's tsunami-capable coastal water-level stations.

The National Weather Service also hosts and staffs the International Tsunami Information Center, operates the Caribbean Tsunami Warning Program, and administers the National Tsunami Hazard Mitigation Program.

Map of all NWS Marine Forecast Areas (Coastal, Offshore and High Seas)


National NWS Marine Forecasts Page:
  • Marine Forecasts
    Forecasts, warnings, observations, maps, pubs, broadcast info, contacts, etc.
High Seas Forecasts and Warnings:
Offshore Forecasts and Warnings:
Coastal and Great Lakes Forecasts and Warnings:
Ice Products:
Model Guidance and Products
Hurricane Forecasts and Warnings:
Tsunami Warnings and Information:
  • NWS Directives (10 - Operations and Services, 10-3 Marine and Coastal Weather Services, 10-6 Tropical Cyclone Weather Services Program, 10-7 Tsunami Warning Services, 10-23 Marine Observation Program)

Awareness Weeks:
Warning and Forecast Area Maps:
Explanation of Codes Used in Various Marine Text Forecasts and Weather Broadcasts:
Service Assessments:
Interagency Agreements:
This and That: