U.S. President Joe Biden speaks during a cabinet meeting in the Cabinet Room of the White House January 5, 2023 in Washington, DC.U.S. President Joe Biden speaks during a cabinet meeting in the Cabinet Room of the White House January 5, 2023 in Washington, DC.

President Joe Biden declared a state of emergency in California on Monday due to a series of winter storms that have left many people without power.

In the past 10 days, at least 12 people have been killed and hundreds of thousands of homes and businesses have been without power. The National Weather Service has warned of a "relentless parade of cyclones" that will increase the risk of flooding.

After a round of heavy rain on saturated soils, there will be a lot of flood potential with rapid river rises, mud slides and burn scar flash floods or debris flows.

During his visit to Mexico City, the president approved the emergency declaration for California. According to the governor, he is in close contact with the White House to make sure the state gets the aid it needs.

A resident walks along a flooded street, after “atmospheric river” rainstorms slammed northern California, in the coastal town of Aptos, January 5, 2023.

The White House said that the president's emergency declaration allows the Department of Homeland Security and the Federal Emergency Management Agency to coordinate all disaster relief efforts.

The counties covered by the declaration are El Dorado, Los Angeles, San Bernardino, San Francisco, Santa Clara, Santa Cruz, Sonoma, and Ventura.

More than 130,000 homes and businesses in California are still without power, according to data from Power Outage.us. Pacific Gas and Electric, the state's largest power company, said on its website on Sunday that more than 4,100 crews are staged throughout its service area, which includes the regions most affected by the storms.

A flooded street after a rain storm in the Aptos Beach Flats neighborhood in Aptos, California, US, on Sunday, Jan. 8, 2023.

When a cold air mass collides with a warm air mass, it's called a bomb cyclone.

The ground in California is so saturated that it is more vulnerable to flooding in the upcoming storms, according to the National Weather Service.