The size of California's McKinney Fire surpassed that of a blaze to the south overnight to become the state's largest of 2022.
The 51,468-acre blaze near the state's northern border has thrived on deadly heat in the Pacific Northwest that has preliminarily been linked to the deaths of seven people in Oregon.
On Saturday, Gov. Gavin Newsom proclaimed a state of emergency for the county. It unlocks additional state and federal firefighting and recovery funds.
It was only a week ago that the 19,000-acre Oak Fire about 400 miles south, in Mariposa County, became the state's largest of the year. That blaze, roughly 40 miles from the edge of Yosemite National Park, was 64 percent contained Sunday.
Late afternoon heat in Oregon-adjacent Siskayou County was measured at 99 degrees Sunday. A red flag warning, which tells residents the most volatile wildfire conditions are present, and an excessive heat warning, were in effect though late Sunday evening.
While officials reported the McKinney Fire seemed to mellow slightly Saturday night amid the added darkness of a toxic fog known as smoke inversion, it roared back to life past midnight and continued to threaten an estimated 400 structures, according to a U.S. Forest Service update Sunday.
The prognosis for the new week was a mixed bag. Federal and state fire officials fear the prospect of dry lightning from thunderstorms moving into the area through at least Wednesday. The National Weather Service forecast a small chance of rain in the mix for Monday.
Any dry lightning has the potential to expand the McKinney Fire's footprint, officials said. In fact, it already happened overnight with a strike near Doggett Creek, north of the main fire, U.S. Forest Service officials said in their latest report.
"These conditions can be extremely dangerous for firefighters, as winds can be erratic and extremely strong, causing fire to spread in any direction," they said.
The McKinney fire's growth favored movement north toward Oregon and west toward the heart of the Pacific Coast Ranges, officials said.
A separate, 300-acre blaze being called the China Fire was nearby and part of the U.S. Forest Service's coverage of the McKinney Fire, but so far it has not emerged with the state's largest wildfire.
Fuel, including timber and brush, was extremely dry in a third year of continuous drought in California.
No single condition for catastrophic fire was lacking in Siskayou County: While winds were not tornadic, forecasters said gusts of 30 to 50 mph were possible in thunderstorms.
Mandatory evacuations for more than 2,000 residents remained in place for multiple communities in the county.