Charleston, SC National Weather Service

Marine Zone Expansion to 60 NM Offshore

OVERVIEW

Beginning on or about March 3, 2026, the National Weather Service (NWS) Weather Forecast Office (WFO) Charleston, SC (CHS) will assume forecast, watch, and warning responsibility for the coastal waters from the South Santee River south to the Savannah River from 20 to 60 Nautical Miles (NM) offshore. Routine forecast services for these waters were previously the responsibility of the Ocean Prediction Center (OPC), with warning responsibility divided between WFO CHS and OPC. This change is part of a regional improvement that will result in all forecasts and warnings for coastal waterways within 60 NM of shore originating from the local WFO across the entire Contiguous United States (CONUS). There will be no change to the current forecast and warning services provided by WFO CHS for coastal waterways within 20 NM of shore or between 20 to 60 NM off the Georgia coast.

JUSTIFICATION

The coastal Atlantic waters are a major source of commerce for South Carolina and Georgia, frequented by commercial, recreational, and research vessels year-round. Major shipping lanes pass just off our coast, with the ports at Savannah, GA and Charleston, SC serving as some of the Nation's busiest ports for container, breakbulk, bulk, and vehicle freight. Additionally, fishermen often leave local ports bound for offshore fishing sites such as artificial reefs and the Gulf Stream. These activities primarily take place within 60 NM of shore, with mariners depending on reliable weather forecasts from the National Weather Service to ensure the safety of themselves and their crew, passengers, and cargo while on the water.  

With the redesignation of all forecast and warning responsibility for the coastal waters within 60 NM of shore to the local WFO, users will experience these benefits:

1. Improved forecast service continuity, with local WFOs now responsible for issuing routine forecasts and warnings for all marine waters out to 60 NM offshore for the entire CONUS.

2. Increased number of forecast parameters with temperature, precipitation chances, and weather type among the parameters that are now available for mariners from 20 to 60 NM offshore out to 5 days in the future.

3. Improved forecast resolution, with point and click forecast capability now enabling mariners to get hourly forecasts for specific points (such as offshore artificial reefs) anywhere within 60 NM of shore out to 5 days in the future.

4. Expanded suite of short and long-fused watch/warning and advisory products to alert mariners to the potential for a variety of hazardous weather conditions.

5. WFO’s now have the capability to deliver Impact-based Decision Support Services (IDSS) to partners in support of incident response for incidents that occur anywhere within 60 NM of shore. 

ZONE CHANGE DESCRIPTIONS

The above graphic shows the new alignment of marine forecast zones with light and dark blue zones now being the responsibility of the local WFO. All coastal waters to 60 NM offshore from south of  the South Santee River to the Savannah River will now receive forecasts and warnings from NWS CHS.

FORECAST RESOURCES

NOAA Weather Radio

One of the most immediate and reliable ways to receive forecasts, watches, and warnings for the waterways of South Carolina and Georgia is through NOAA Weather Radio. The following table outlines the best transmitter for area waterways:

Online

Routine forecasts and warnings for mariners in South Carolina and Georgia waters can be found online at weather.gov/chs/marine.

Alternatively, to get the forecast for a specific point, visit weather.gov/marine/point and click on the map or enter your lat/lon.

Telephone

Recorded area marine forecasts can be accessed by calling 843-747-5860 Option #2.

CONTACT

Please submit any questions or comments to:

Carl Barnes

Science and Operations Officer

National Weather Service

Charleston, SC

5777 South Aviation Avenue

North Charleston, SC 29406