The National Weather Service (NWS) of the U.S. provides many products and services for marine areas in international waters. One of the primary international services provided by the NWS is its involvement in the Worldwide Met-Ocean Information and Warning Service (WWMIWS).
The NWS (along with other Countries) provides marine meteorological warnings and meteorological forecast information to mariners via International Enhanced Group Call (EGC) Service (satellite distribution) and NAVTEX (radio signal distribution), as part of the World Meteorological Organization's (WMO) Worldwide Met-Ocean Information and Warning Service (WWMIWS), within the framework of the International Maritime Organization's (IMO) Global Maritime Distress & Safety System (GMDSS). More information about the GMDSS is available at the GMDSS Master Plan module of GISIS.
The worlds' oceans have been divided into 21 areas, called METAREAS, for the provision of marine meteorological information and services to shipping. The NWS is responsible for providing forecasts and warnings for METAREAs IV and XII. Below is a map of the world's METAREAs. If you are interested in forecasts and warnings for these METAREAs, visit the Worldwide Met-Ocean Information and Warning Service (WWMIWS) website.
In February 1999, the Global Maritime Distress and Safety System (GMDSS) became the primary international means for disseminating Maritime Safety Information (MSI) to mariners. The goals of the GMDSS are to provide more effective and efficient emergency and safety communications and disseminate Maritime Safety Information (MSI) to all ships on the world's oceans regardless of location or atmospheric conditions. MSI includes navigational warnings, meteorological warnings and forecasts, and other urgent safety related information. GMDSS goals are defined in the International Convention for the The Safety Of Life At Sea (SOLAS) and affects vessels over 300 gross tons and passenger vessels of any size. Under the SOLAS, reception of MSI is mandatory, While at sea, vessels must maintain radio watches for broadcasts of maritime safety information on the appropriate frequency or frequencies on which such information is broadcast for the area in which the ship is navigating." 47 CFR 80.1123(b). SOLAS was originally developed in 1914 after the sinking of the Titanic in 1912.
The National Weather Service participates directly in the GMDSS by preparing meteorological forecasts and warnings for broadcast via NAVTEX, HF Narrow Band Direct Printing (NBDP) and approved satellite providers SafetyNET and Safetycast.
NAVTEX and NBDP use radio signals to broadcast information. The US Coast Guard operates stations within the METAREAS and is a partner with the NWS in GMDSS participation.
NAVTEX is an international automated medium frequency (518 kHz) direct-printing service for delivery of navigational and meteorological warnings and forecasts, as well as urgent marine safety information to ships. It was developed to provide a low-cost, simple, and automated means of receiving this information aboard ships at sea within approximately 200 nautical miles of shore. NAVTEX stations in the U.S. are operated by the U.S. Coast Guard. There are no user fees associated with receiving NAVTEX broadcasts. Within the U.S., there are no NAVTEX broadcasts on the alternate designated frequencies of 490 or 4209.5 kHz, however, the NAVTEX station in the Marianas (Guam) will temporarily broadcast on frequency 4209.5 kHz using B1 character while repairs are being made to the station which broadcasts on 518 kHz.
Here is some detailed information about NAVTEX broadcasts from the US Coast Guard, including links to maps of coverage areas.
SITOR (NBDP) is similar in many respects to NAVTEX but does not offer all of the same functionality such as avoiding repeated messages.
For more information related to NAVTEX and NDBP, including station identifiers and weather broadcast schedules, visit https://www.weather.gov/marine/gmdss and click on the NAVTEX tab.
Text forecasts produced by the NWS for the 15 NAVTEX areas are linked to here: https://www.weather.gov/marine/forecast#navtex. The NAVTEX forecast is a blend of the outer coastal waters (typically 20 to 60 nm offshore) and the Offshore forecasts (typically beyond 60 nm offshore).
For satellite dissemination (International Enhanced Group Call (EGC) Service) of high seas forecasts and warnings for METAREAs IV and XII, the NWS produces a METAREA Forecast for each area four times daily. The forecasts are broadcast by two satellite companies, Inmarsat and Iridium, four times daily. The NWS also sends Tropical Cyclone Bulletins and Tsunami Bulletins when applicable to areas IV and/or XII for broadcast by the satellite companies.
The NWS began using SafetyNET II services from Inmarsat operationally on January 22, 2024. Prior to that, the NWS used SafetyNET from 1999 to January 2024. SafetyNET II is a part of the GMDSS, is the new generation international broadcast and automatic reception service for Maritime Safety Information. SafetyNET II is an enhancement to the current SafetyNET system, and provides a user-friendly, interactive web interface for Maritime Safety Information Providers to create their Maritime Safety Information messages and delivered them simultaneously over multiple Inmarsat networks, including Inmarsat C, Mini C and Fleet Safety. For more information about Inmarsat and SafetyNET, including a table of satellite identifiers, product IDs and broadcast times, visit https://www.weather.gov/marine/gmdss and click on the Inmarsat-C SafetyNET II tab.
The NWS began its operational phase with Iridium's SafetyCast on 6/12/2023. Iridium SafetyCast is an internationally adopted, automated satellite system for promulgating weather forecasts and warnings, marine navigational warnings and other safety related information to all types of vessels and is part of the Global Maritime Distress and Safety System (GMDSS). There are no user fees associated with receiving SafetyCast broadcasts. For more information about Iridium and SafetyCast, including a table of satellite identifiers, product IDs and broadcast times, visit https://www.weather.gov/marine/gmdss and click on the SafetyCast tab.
NWS international products and services are not limited to those required under GMDSS regulations. The NWS provides High Seas Forecasts for 7 different zones within the Atlantic and Pacific Oceans. Links to text versions of all NWS High Seas Forecasts and Warnings, including the METAREA IV and XII forecasts, can be found here. The NWS also provides Offshore Forecasts and Warnings for 11 regions of the Atlantic and Pacific Oceans. NWS Offshore Forecasts and Warnings can be found here.
The National Hurricane Center provides briefings to support the USCG missions in the Gulf of America and the southwestern Atlantic.
To see a map showing the general areas of all NWS marine forecast and warning zones, click here.
The NWS also provides radiofax (also called weatherfax) charts of marine forecasts and analyses. The NWS radiofax program prepares high seas weather maps via four U.S. Coast Guard sites: Boston, New Orleans, Pt. Reyes, and Kodiak and the Defense Department transmitter site in Honolulu. These broadcasts are prepared by the Ocean Prediction Center , National Hurricane Center, Honolulu Forecast Office. and Anchorage Forecast Office. You can also find limited satellite imagery, sea surface temperature maps and text forecasts. For more information on radiofax charts including broadcast stations (operated by the US Coast Guard) products, schedules and links to individual charts, click here.
Information about the weather broadcasts from the US Coast Guard, including transmitters, frequencies, schedules and products, is located here.
Mariners can request and receive these charts, along with NWS text products, via email using our FTPMail system. Here is information on how to use the FTPMail system.
The National Data Buoy Center (NDBC) provides marine observations for international waters. For other types of marine weather observations, scroll over the Observations tab on the NWS Marine Program's home page.
Three National Centers and the Anchorage, AK forecast office provide graphical and digital marine products and services for international waters. For more information, click on the links... Ocean Prediction Center , National Hurricane Center, Honolulu Forecast Office. and Anchorage Forecast Office.
