The Park Fire had burned more than 141,640 hectares about 144km north of the state capital city of Sacramento as of Saturday evening (local time), according to the California Department of Forestry and Fire Protection, or Cal Fire.
Cooler temperatures and more humid air were expected in the region, potentially helping efforts to slow the spread of the fire, which was 10% contained as of Saturday evening.
The fire has destroyed 134 structures, authorities said.
Evacuation orders and warnings were issued for multiple communities in several counties, including a warning for Paradise, the town that was devastated by the 2018 Camp Fire, the deadliest in the state's history.
United States President Joe Biden has been briefed on the fire and directed his team to do everything possible to support efforts to fight it, a White House official said.
A man was arrested on Thursday on suspicion that he started the Park Fire by pushing a flaming car into a gully on Wednesday afternoon.
The fire was the largest of dozens of active blazes across the country that have burned 809,000ha, according to the National Interagency Fire Center.
In Oregon, several fires were burning, including the Durkee Fire, which had scorched more than 116,000ha in the eastern part of the state, authorities said.
A firefighter died after a single-engine tanker crashed near the Falls Fire in southeastern Oregon, the US Forest Service said in a statement on Friday.
