Cooler weather did little to diminish athat is threatening more than 1,400 buildings, according to fire officials. The fire burning northwest of Sacramento grew overnight to 134 square miles (347 square kilometers), California Department of Forestry and Fire Protection said Thursday.
But CalFire said crews gained some ground and increased containment to 30 percent -- up from 25 percent the previous day.
Roughly 2,500 people have been forced from their homes since the blaze started on Saturday. Officials have lifted some mandatory evacuations but it's not known how many people have been allowed to return home.
"It's a little nerve-racking because grass fires move so fast," said Steve Black, one property owner who spoke to CBS News.
So far no structures have been damaged or destroyed.
Wildfires have also , where the Spring Fire alone has devoured an area larger than the size of Detroit, leaving 100 homes destroyed. In Utah, officials ordered residents to leave, as firefighters struggled to contain flames east of Salt Lake City.
Huge wildfires roared across the bone-dry western USA on Thursday, including Colorado's Spring Creek Fire, the state's third-largest on record.
That fire has destroyed 100 homes and forced the evacuations of 2,000 other homes. The blaze is near Fort Garland, roughly 205 miles southwest of Denver.
Nearly 1,000 firefighters worked to gain control of the fire in unpredictable winds, but it's been only slightly contained since it ignited June 27. As of Thursday morning, the fire was 161 square miles, roughly seven times the size of Manhattan.
Jesper Jorgensen, 52, was arrested on criminal charges of arson related to starting the fire. According to an arrest affidavit, he was cooking meat for several hours in a fire pit the night before the blaze started.
Another Colorado blaze, the Lake Christine Fire, forced evacuations early Thursday morning about 20 miles northwest of Aspen. The fire jumped from less than 1 square mile to about 4 square miles Wednesday, the Denver Post reported.
The wildfire may have been started by tracer rounds fired at a shooting range.
In Northern California, the County Fire has burned about 134 square miles and is 27 percent contained in Napa and Yolo Counties. The blaze threatens 1,500 structures, but none has been destroyed or damaged.
Roughly 2,500 people have been forced from their homes since the blaze started Saturday. This week in the Bay Area, about 75 miles south of the fires, falling ash was reported, and the San Francisco sky turned orange from the smoke, weather.comreported.
Rain is unlikely in the West on Thursday or Friday. Some monsoon-type thunderstorms could arrive over the weekend in the Southwest, according to AccuWeather.
“We’re looking at hot weather to continue with potential for some scattered afternoon and early nighttime thunderstorms that could bring some spotty rain but could also cause lightning-induced fires,” AccuWeather meteorologist Ken Clark said.
Overall, more than 60 blazes are burning across the western continental USA and in Alaska, the National Interagency Fire Center said. In 2018, wildfires have charred 4,272 square miles in the USA, about 555 square miles above average.