King tides inundate streets and flood homes and businesses along both US coasts

King tides have inundated parts of both U.S. coasts, flooding streets and sending seawater into homes and businesses in beach communities in California, Florida and the Carolinas.

The tides began with the full moon earlier this week and could cause flooding in some areas into the weekend, forecasters said. King tides are caused by the gravitational pull and alignments of the Earth, moon, and sun. They can occur several times a year and last several days.

This week's king tides have been exacerbated by additional factors, forecasters said Wednesday.

In Florida, strong high pressure to the north and low pressure over the Caribbean were causing increased swells, Chris Fisher, a National Weather Service meteorologist in Miami, said.

Along the California coast, the ongoing super El Niño has warmed the ocean, leading to an increased volume of seawater. Another factor was the occurrence of Kelvin waves , a series of pulses of warm water that lift the sea level, said Roger Gass, a meteorologist with the weather service's Bay Area forecast office in Monterey.

King tides, like their name, are definitely noticeable. Residents don't need a beach to see the ocean. The ocean came to them.

In Southern California, Huntington Beach residents placed sandbags outside of homes Wednesday to try to keep floodwaters out. Some people used paddleboards and surfboards to move about the streets. Stretches of the Pacific coast Highway were closed, and tides were expected to approach record levels in Orange and San Diego counties.

In the northern part of the state, minor flooding was expected through Saturday in low-lying areas along shorelines and tidal waterways during peak high tides, the weather service said.

Gass said the coastal flooding generally occurred within 1 1/2 hours before and after high tides, which are peaking 1.9 feet (about a half-meter) above normal in Northern California.

Most of Florida’s Atlantic coast was under flood warnings through early Friday. Street flooding also was reported in South Carolina coastal cities, including Charleston and Myrtle Beach, and rip currents were possible as far north as North Carolina's Outer Banks.

“It’s been a rough beach week,” Fisher said. “We’ve had a high risk of rip currents and some high surf out there. The beach conditions are going to continue to be rough through the weekend. It’s been a good week to stay out of the water and stay away from the beaches.”

In Fort Lauderdale, Florida, getting to the multiple waterfront venues at what’s billed as the world’s largest-in-water boat show was tricky, requiring driving through flooded streets next to marinas, hotels and convention centers.

Virginia Key, a barrier island in Miami, saw its highest king tide and the third-highest water level since records were first kept going back three decades, Fisher said.

“The only times we've seen higher was during hurricanes,” Fisher said. “It's historical from a king tide perspective.”