[Daily Mail, where America gets its news] Gavin Newsom has declared a state of emergency as California braces for Hurricane Hilary to hit today.

Residents in the south of the state have been given evacuation orders ahead of the historic storm making landfall around 1pm.

The governor's office has tried to reassure them extensive preparations are underway, including the deploying of 'more than 7,500 boots on the ground'.

But panic buying has set in and some supermarket shelves in San Diego and Los Angeles were stripped bare of essentials such as water and tinned food.

The tropical storm, the first set to make landfall in California since 1939, could impact more than 42million people.

The state has prepared water rescue teams, California National Guard personnel and flood fighting equipment ahead of Hilary's arrival, officials said.

Hurricane Hilary is currently registered as a Category 1 storm, downgraded from a Category 2 on Saturday night.

The National Hurricane Center warned Hilary could bring 'catastrophic and life-threatening flooding' to Baja California and the Southwestern US.

The threat has triggered California's first ever tropical storm warning extending from the state's southern border to just north of Los Angeles.

The storm may dump more than a year's worth of rain on parts of the Southwest, the National Weather Service has warned.

Part of Nevada and Southern California may see as much as 10 inches of rainfall hit in a matter of hours.

Evacuation notices have been issued to residents in Oak Glen, Forest Falls, Mountain Home Village, Angelus Oaks, and NE Yucaipa by the San Bernardino County Sheriff's office.

On Saturday night the storm had sped up, moving at around 18 mph, around 500 miles southeast of San Diego.

It is expected to continue to weaken as it moves north-northwestward through cooler waters toward Southern California.

However, the harshest effects are expected later on Sunday and into Monday including possible winds of 90 miles per hour.

Schools in Mexico's Cabo San Lucas were being readied to use as temporary shelters while police patrolled closed beaches in the Baja California Sur state to keep swimmers out.