More than 6,800 wildfires large and small have blackened an estimated 1.7 million acres (689,000 hectares) within California alone this season, stretching available firefighting forces and equipment dangerously thin.
US President Joe Biden has approved a disaster declaration for California and will travel to Sacramento to survey the damage from recent wildfires.
The blazes in California have been stoked by extremely hot, dry conditions that experts say are symptomatic of climate change during a summer fire season shaping up as one of the most destructive on record.
"President Joseph R Biden, Jr. declared that a major disaster exists in the State of California and ordered Federal assistance to supplement State, tribal, and local recovery efforts in the areas affected by the Caldor Fire beginning on August 14, 2021, and continuing", the White House said late on Sunday.
Boost infrastructure and fight global warming
Biden said last week that wildfires, hurricanes and floods were hitting every part of the United States, with more than 100 million Americans affected this summer alone, as he pressed for investments to boost infrastructure and fight global warming.
Biden made fighting climate change a key plank of his 2020 presidential campaign and a top priority of his administration but some of his goals rely on getting the US Congress to pass multi-trillion-dollar legislation on infrastructure and other priorities.
This month, Biden declared an emergency in California and ordered federal assistance to boost responders' efforts to battle the Caldor fire.
"Additional designations may be made at a later date if requested by the State and warranted by the results of further damage assessments", the White House said on Sunday.
The Caldor fire, burning since mid-August, is 65 percent contained. It has led to five injuries and damaged 81 residential, commercial and other structures while destroying over a thousand such structures, according to authorities.
Southwesterly winds are forecast through most of the coming week which could fan the growth of fires in the West Zone, the California Department of Forestry and Fire Protection (Cal Fire) said late on Sunday.