Guam, Northern Mariana Islands Moderate Coastal Flood Watch | Effective 10/16/2026 05:48

* WHAT...For the High Surf Warning, large, hazardous breaking waves of 7 to 9 feet Saturday afternoon will become dangerous, building to as high as 35 feet for Guam, 25 feet for Rota and 20 feet for Tinian and Saipan. For the Coastal Flood Watch, significant coastal flooding possible. * WHERE...For the High Surf Warning, initially east facing reefs of Guam, Rota, Tinian, and Saipan; spreading to all reefs through Sunday afternoon. The Coastal Flood Watch is also for all reefs of the Marianas. * WHEN...For the High Surf Warning, from 5 PM Saturday to 4 AM ChST Monday. For the Coastal Flood Watch, from Saturday afternoon through late Sunday night. * IMPACTS...Numerous roads may be closed. Low lying property including homes, businesses, and some critical infrastructure may be inundated. Some shoreline erosion may occur. Breaking waves can sweep people off jetties and docks, and into dangerous seas. Life-threatening swimming conditions and significant beach erosion can be expected. Coastal inundation of 5 to 7 feet for Guam, 2 to 4 feet for Rota and 1 to 3 feet for Tinian and Saipan is possible along with coastal flooding and beach erosion. * ADDITIONAL DETAILS...As TS Champi approaches the Marianas, surf conditions are expected to deteriorate rapidly, with surf reaching 9 feet Saturday afternoon, building to dangerous/deadly levels through Saturday night.