A fast-moving wildfire burning near Yosemite national park is threatening rural communities as millions of people in California and across the US west swelter under a brutal heatwave that is predicted to persist through the weekend.
The French fire broke out on Thursday and grew to more than 900 acres (364 hectares) by Friday afternoon. The fire is 15% contained with “multiple evacuations and road closures in place”, according to local fire officials.
Footage posted on social media showed flames and smoke billowing on Thursday night over the Gold-Rush era town of Mariposa, a community in the Sierra Nevada foothills about 40 miles outside the national park. The area is under an excessive heat alert with temperatures due to top 100F (38C) on Friday.
Bulldozers and crews built a line across the entire eastern side of Mariposa and are making progress in bringing the fire under control.
“Winds have calmed which has helped firefighters make progress overnight,” according to a status report from Cal Fire, the state’s wildfire agency.
The fire is one of more than a dozen burning across the state, including several that broke out on the Fourth of July. Further north, firefighters were gaining ground against the Thompson fire near the city of Oroville in Butte County, which has burned more than 3,700 acres and prompted evacuation orders for thousands of people.
On Friday, containment of the Thompson fire had increased to 29% and evacuated residents were allowed to return home as crews continue to battle the flames in scorching heat. Officials have warned of hot temperatures in the area that could hit 108F, with even hotter weather expected into the weekend.
California has faced a number of spring and early summer wildfires, thanks to a wet winter that left landscapes coated in grasses that were primed to burn as the summer heated up.
The excessive heat will only dry out the landscapes further, adding to the threat of an active wildfire season in the months ahead. Officials had feared that fireworks and other Fourth of July celebrations would add to the risks.
“The combination of events has presented a huge challenge for firefighters. It is so incredibly dry out there,” said Ed Fletcher, a public information officer with Cal Fire, this week.
Meanwhile, residents across the US west are dealing with stifling temperatures. About 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 south-west, the National Weather Service said.
“Numerous record-breaking temperatures can be expected through the next few days,” according to a NWS briefing. The west coast will hover 15 to 30F above average, with many towns and cities reaching close to 110F (43C) or above on Friday.
The extreme heat was to blame for a fish die-off in the San Francisco Bay Area this week. About 1,000 fish have died since 3 July at Lake Elizabeth in Fremont, California. Temperatures in the city about 36 miles south-east of San Francisco reached the mid- to upper 90s, causing the oxygen levels in the lake to drop.
“Fish dying off in Lake Elizabeth in the summer is not completely unusual. We do get a small number of fish that die off every year,” city spokesperson Geneva Bosques said. But the intense heat paired with a dip in lake levels means more fish fighting for less oxygen, resulting in bigger die-offs.
The National Weather Service in Flagstaff, Arizona, posted on social media: “Expect only subtle changes to our daily high temperatures through the weekend.”
“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 is expected to be 115F (46C), and Palm Springs, California, where it will reach 119F (48C). Las Vegas is expected to hit 118F on Monday, potentially breaking an all-time record.
Elsewhere, ferocious heat will also prevail from Mississippi to Florida, and north along the east coast to Pennsylvania, where temperatures will exceed 100F (38C).
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”.
More on extreme heat and wildfires in the US