Thousands of people are fleeing wildfires in California, while on the other coast, residents in the mid-Atlantic are bracing for a new round of torrential storms and potential flooding on Thursday.
A dangerous heat wave will bring triple-digit temperatures to much of the Southwest and parts of the western United States through Friday. High temperatures could reach up to 110 degrees in inland cities and up to the mid-120s in desert areas, forecasters say.
More than 30 million people on the West Coast -- from Washington state to the California-Mexico border -- are under a heat advisory or watch Thursday as a strong ridge of high pressure blocks any major cold fronts or low pressure systems from pushing through the area, CNN meteorologist Haley Brink said.
The National Weather Service is warning residents of heat-related illnesses, power outages and critical fire conditions.
Wildfires in California
The heat is set to create even more challenges for the more than 17,000 firefighters battling wildfires across the western states on Thursday.
Crews descended into the San Bernardino National Forest on Wednesday trying to put down the fast-growing Cranston Fire.
The blaze has quickly spread, forcing 3,200 people out of their homes and destroying five residential structures, the US Forest Service said. The town of Idyllwild, the community of Mountain Center, and the areas of Apple Canyon, Hurkey Creek and Lake Hemet -- or a total of about 16,000 people -- are under evacuation orders.
The Cranston Fire has burned 4,700 acres since it started Wednesday and is only 5% contained, officials said.
Authorities believe Brandon N. McGlover is responsible for starting the Cranston Fire and several others. The 32-year-old was arrested Wednesday and is now facing five counts of arson to wildland, the Riverside County Fire Department and Cal Fire said.
Another fire, the Ferguson Fire, has prompted the closure of the most iconic areas of Yosemite National Park until Sunday.
"Get yourself out of here if you can," said Michael Reynolds, the park's superintendent.
The blaze, which is raging west of the park, has burned 41,576 acres and is 26% contained, the US Forest Service said.
The fire began July 13 in Merced River Canyon. Braden Varney, 36, a heavy fire equipment operator, died the day after the blaze began when the bulldozer he was operating rolled over, according to the California Department of Industrial Relations.
Six firefighters have been injured while battling the blaze, fire officials said.
More flooding threatens mid-Atlantic
The Mid-Atlantic has been swamped by rainfall for several days and forecasters say a few more storms are on the way.
About 6 to 12 inches of rain fell over the past five days in several states, including Pennsylvania, Maryland, New Jersey and Virginia.
In Dunkirk, Maryland, more than 16 inches of rain were recorded by Wednesday, according to rainfall data from the National Weather Service.
As many as 7 million people remain under a flood warning across areas of Pennsylvania and Maryland, where the ground is already saturated by rainfall.
"The additional rainfall will aggravate ongoing flooding, and perhaps initiate new flooding," the National Weather Service said in a statement.
The cities of Baltimore and Gettysburg are also included in the warnings.
The body of an 18-year-old man was recovered Wednesday along a flooded creek in Butler Township, Pennsylvania, state police said.
Alejandro Morales had been reported missing after his van apparently became stranded in high water on Monday, CNN affiliate WHTM reported.
A helicopter spotted Morales' body on Wednesday after crews had suspended the search due to rising waters and continued rain, police said.
Authorities are also searching for a 19-year-old woman who was swept away along the same creek on Monday.