Full Moon and El Nino Drive Historic Tides Across US Coasts

Seawater has crossed into streets, homes, and businesses along the East and West coasts this week.

The flooding stems from king tides triggered by the full moon earlier in the week. These events occur when the gravitational pull of the Earth, moon, and sun align. While they happen several times a year, forecasters noted that specific weather patterns intensified this week's impact.

Chris Fisher, a meteorologist for the National Weather Service in Miami, explained that strong high pressure to the north and low pressure over the Caribbean increased swells in Florida. On the West Coast, Roger Gass, a meteorologist with the Bay Area forecast office in Monterey, cited the ongoing super El Nino. This phenomenon has warmed the ocean and increased seawater volume. Gass also identified Kelvin waves, which are pulses of warm water that raise sea levels, as a contributing factor.

In Southern California, residents of Huntington Beach placed sandbags outside their homes on Wednesday to block incoming water. Some commuters used paddleboards and surfboards to travel through flooded streets. The Pacific Coast Highway was closed in sections, and tides were expected to approach record levels in Orange and San Diego counties.

In Northern California, high tides peaked at 1.9 feet above normal. The weather service predicted minor flooding in low-lying areas along shorelines and tidal waterways through Saturday. Gass noted that coastal flooding typically occurs within an hour and a half before and after high tide.

Florida's Atlantic coast remained under flood warnings through early Friday. Street flooding was reported in South Carolina coastal cities, including Charleston and Myrtle Beach. Rip currents were possible as far north as North Carolina's Outer Banks. Fisher described the conditions as a rough week for beachgoers, citing high risks of rip currents and high surf. He advised staying out of the water through the weekend.

In Fort Lauderdale, Florida, drivers faced flooded streets to reach the world's largest in-water boat show. The event includes multiple waterfront venues near marinas and hotels. Virginia Key, a barrier island in Miami, recorded its highest king tide and third-highest water level since records began three decades ago. Fisher stated that only hurricanes have produced higher water levels in that location.