Sept. 21, 2026 12:35 PM PT

A tropical storm rapidly intensifying into a “very dangerous” hurricane in the Pacific Ocean could potentially bring more muggy weather to Southern California, forecasters say.

Tropical Storm Polo is expected to strengthen to a major hurricane as it moves closer to the coast of southwestern Mexico, bringing heavy rainfall that could trigger life-threatening flooding and landslides to the country, according to the National Hurricane Center’s Monday forecast.

Although it’s still too early to tell, Polo could pull tropical moisture into Southern California, depending on patterns in the upper levels of the atmosphere, said Bryan Lewis, a meteorologist with the National Weather Service in Oxnard.

Previous Pacific storms, most recently Hurricane Marie, have blanketed the region in unusually warm, humid air more reminiscent of the South.

Polo is the 16th named storm to form in the eastern Pacific this year.

Any effects from Polo probably won’t reach Southern California until toward the end of the weekend, at the earliest, according to Lewis.

The biggest impact would most likely be the potential for increased surf from a south swell, but the magnitude depends on the track of the system and is tough to pin down this far out, Lewis said.

“After almost an entire summer of southern swell after southern swell, there could be some issues for those vulnerable coastlines,” he said.

Already this year, multiple counties and towns have declared local emergencies as a spell of powerful tropical storms from the Pacific generated high surf that eroded local beaches.

Those include Laguna Beach, Dana Point and Carlsbad, which cited coastal erosion and sand loss.

El Niño typically results in an unusually active hurricane season in the eastern Pacific and heavy winter rainfall in Southern California, and this El Niño is predicted to be the strongest in at least a generation.

Gov. Gavin Newsom has declared a statewide emergency in anticipation of this winter’s storms, citing fears the weather pattern could bring high surf and high-impact storms to the state.

Times staff writer Grace Toohey contributed to this report.