The U.S. National Hurricane Center said a tropical storm watch has been issued for Southern California, the first time it has ever done that.

Winds at 145 MPH on Friday

Hilary had sustained winds near 145 mph early Friday and was expected to strengthen a bit more before starting to weaken. It nevertheless was expected to still be a hurricane when approaching Mexico’s Baja California peninsula on Saturday night, and a tropical storm when approaching Southern California on Sunday.

No tropical storm has made landfall in Southern California since Sept. 25, 1939, according to the National Weather Service.

Early Friday, Hilary was centered about 360 miles south-southwest of Los Cabos on the southern tip of the Baja peninsula. It was moving northwest at 10 mph and was expected to turn further toward the north.

The Mexican government extended its hurricane watches and warnings northward for parts of Baja California peninsula and also issued a tropical storm watch for parts of mainland Mexico.

“Heavy rainfall in association with Hilary is expected to impact the Southwestern United States through next Wednesday, peaking on Sunday and Monday,” the hurricane center said. It said there was a substantial danger of flash flooding in an area stretching from San Diego to Las Vegas.

“Rainfall amounts of 3 to 6 inches, with isolated amounts of 10 inches, are expected across portions of southern California and southern Nevada, which would lead to significant and rare impacts. Elsewhere across portions of the Western United States, rainfall totals of 1 to 3 inches are expected.”

SpaceX Launch Delayed

SpaceX  delayed the launch of a satellite-carrying rocket from a base on California’s central coast until at least Monday. The company said conditions in the Pacific could make it difficult for a ship to recover the rocket booster.

The Mexican government said a weakened Hilary might skim a sparsely populated area on the western edge of the Baja peninsula early Sunday, and then perhaps hit a more heavily populated area of the coast Sunday night between the cities of Playas de Rosarito and Ensenada, in Baja California state.

Meanwhile, the city of Yuma was preparing Thursday by providing residents with a self-serve sandbag filling station.

The sandbag station will be stocked with sand and empty bags for self-filling while supplies last. Residents were allowed five sandbags per vehicle.