By David Swanson
MARIPOSA, Calif. (Reuters) -Dangerously hot conditions will dominate over the rest of the July Fourth holiday weekend in much of the U.S. West Coast, Southeast and Middle Atlantic seaboard, forecasters said on Friday, as California firefighters battled one of the first big wildfires of the season.
Around 108 million Americans will spend the remainder of the weekend under excessive heat advisories, with record-breaking temperatures forecast for many spots in California, southern Oregon and the Southwest, the National Weather Service said.
The West Coast will hover 15 to 30 degrees above average, reaching 110 Fahrenheit (43 Celsius) on Friday.
"Expect only subtle changes to our daily high temperatures through the weekend," the National Weather Service in Flagstaff, Arizona, said on X.
"Where did you go, monsoon? Hurry back," it said, referring to a recent bout of torrential rain in the area, which is usually bone-dry this time of year.
Some of the hottest spots will include Phoenix where it will be 115 F (46 C), Washington D.C. where it is expected to climb to 100 F (38 C), and Palm Springs, California, where it will reach 119 F (48 C). That is almost three times as hot as it will be in Yellowstone National Park in Montana, where the forecast was for temperatures to dip to 37 F on Friday night.
The weather service urged people to stay hydrated, out of the sunlight, and in buildings with sufficient air-conditioning.
Stifling heat will also prevail from Mississippi to Florida, and north along the Eastern Seaboard to Pennsylvania, where temperatures will reach past 100 F (37 C).
The National Weather Service warned that hot overnight conditions across the Mississippi Valley could lead to "a dangerous situation for those without access to adequate cooling".
Hot, dry and windy conditions in the West were forcing fire officials and forecasters to issue warnings about the risk of wildfires.
The so-called Thompson Fire in Butte County, California, about 65 miles (105 km) north of Sacramento, has scorched almost 6 square miles (16 square kilometers) of scrub and brush since it started on Tuesday.
As of Friday morning, the fire was 46% contained after forcing some 13,000 households to evacuate.
Most evacuation orders were lifted early on Friday morning as firefighters made progress controlling the blaze, which had damaged or destroyed about 30 structures, fire officials said.
Some 225 miles (362 km) south, firefighters battled the French Fire that threatened Mariposa, a gateway to Yosemite National Park. The 800-acre (323-hectare) fire was 5% contained as winds calmed on Friday, helping firefighters make progress.
Southern Texas faces a different sort of threat early next week when remnants of Hurricane Beryl are expected to dump heavy rains on the region.
Beryl, the first hurricane of the season, made landfall in Mexico on Friday after killing 11 people as it carved a path of destruction across the Caribbean earlier this week.