Firefighters were battling California's largest wildfire of the summer on Monday, a blaze near famed Yosemite National Park that has forced thousands of people to evacuate, officials said.

The Oak Fire in central California comes as parts of the United States remain in the grip of a sweltering heat wave.

The fire in Mariposa County has engulfed 16,791 acres (6.795 hectares) and is 10 percent contained, Cal Fire, the state fire department, said.

It is the most destructive blaze so far this fire season, according to Cal Fire, destroying more than three times the acreage than the nearby Washburn Fire, which has been nearly 90 percent contained.

But it pales in comparison to last year's Dixie Fire, which burned nearly one million acres.

"What we're seeing on this (Oak Fire) is very indicative of what we've seen in fires throughout California, in the West over the last two years," Jon Heggie, a Cal Fire battalion chief, told CNN.

"These fires are burning with just such a velocity and intensity, it makes it extremely challenging and extremely dangerous for both the public and the firefighters," Heggie said.

"It's moving so quickly it's not giving people a lot of time and they sometimes are just going to have to evacuate with just the shirts on their back," he said.

Jonathan Pierce, a spokesman for the fire department, said low humidity and high temperatures were stoking the blaze.

"We also have a high tree mortality in Mariposa County, so a lot of dead standing trees, a lot of dead trees that are on the ground. That coupled to the topography of the area, which is steep in a lot of places, is leading to extreme fire behavior," he added.

The Oak Fire has forced the evacuation of some 3,000 people so far, officials said, and the hot and dry conditions and steep, rugged terrain of the Sierra Nevada foothills are complicating firefighting efforts.

More than 2,000 firefighters backed by 17 helicopters have been deployed against the Oak Fire, which broke out on Friday near the southwestern edge of Yosemite National Park.

– 'Direct result' of climate change –

California Governor Gavin Newsom declared a state of emergency in Mariposa County on Saturday, citing "conditions of extreme peril to the safety of persons and property."

In recent years, California and other parts of the western United States have been ravaged by huge and fast-moving wildfires, driven by years of drought and a warming climate.

"What I can tell you is this is a direct result of what is climate change," Heggie told CNN.

"You can't have a 10-year drought in California and expect things to be the same," he said. "We're now paying the price for that 10-year drought.

"That drought is what drives what we are calling megafires."

Evidence of global warming could be seen elsewhere in the country, as 60 million Americans were under a heat advisory on Monday.

The National Weather Service said heat advisories are in place in the Southern Plains and Lower Mississippi Valley, while stifling temperatures would ease on Tuesday in the Northeast and mid-Atlantic.

The usually cool Pacific Northwest will see temperatures surpassing 100 or more degrees Fahrenheit (37 degrees Celsius) in the Columbia River Gorge and Columbia River Basin.

The NWS said daily record highs will likely be broken from northern California to the Portland, Oregon and Seattle, Washington areas on Tuesday.

Cities have opened cooling stations and increased outreach to at-risk communities such as the homeless and those without air conditioning.

Various regions of the globe have been hit by extreme heat waves in recent months, such as Western Europe in July and India in March to April, incidents that scientists say are an unmistakable sign of a warming climate.

The extreme weather prompted former US vice president Al Gore, a tireless climate advocate, to issue a stark warning on Sunday about "inaction" by US lawmakers.

Asked whether he believes US President Joe Biden should declare a climate emergency, which would grant him additional policy powers, Gore was blunt.

"Mother Nature has already declared it a global emergency," Gore told ABC.

One person killed fighting Morocco forest fire
Rabat (AFP) July 26, 2022 –

One volunteer firefighter has been killed and another injured in a forest fire in northern Morocco, where new blazes have broken out after a few days of calm, according to local authorities.

The two victims were helping Monday in operations to extinguish a fire in Tanouate province near Fez and Meknes, local sources told AFP.

The injured volunteer was hospitalised but his life was not in danger.

Firefighting services were working overnight to control the blaze after ensuring the safety of villagers, authorities added.

About 33 hectares (82 acres) of forest have been destroyed in the region.

Several outbreaks of varying magnitude have resumed in recent hours in northern Morocco, particularly in Larache province, which was recently devastated by forest fires that left one dead.

The Moroccan government on Friday released emergency aid of nearly 30 million euros ($31 million) to help victims of forest fires and reduce their impact on agricultural activity and the environment.

Forest fires destroyed more than 10,500 hectares in the north of the kingdom in mid-July.

Morocco, which is experiencing severe drought, has been hit by heatwaves over the past month.

Scientists say human-induced climate change is amplifying extreme weather, with global warming leading to increased risks of heatwaves, drought and forest fires.

Dozens evacuated as forest fire rages in Czech Republic
Prague (AFP) July 25, 2022 –

Firefighters in the Czech Republic evacuated dozens of people on Monday as a forest fire ripped through a national park.

The blaze in the Bohemian Switzerland National Park on the Czech-German border comes amid record temperatures.

"Several dozen people had to be evacuated from a tourist resort, a scout camp and from the two communities of Mezna and Mezni Louka threatened by the flames," Milan Rudolf, spokesman for the Czech fire brigade in the Usti nad Labem region told AFP.

No casualties have been reported but "the situation is critical," Czech Environment Minister Anna Hubackova wrote on Twitter after visiting the area where the alarm was first raised on Sunday morning.

Forty-six Czech firefighting units tried to extinguish the fire on Monday. They were helped by three German units, which left for the German side of the border where the fire started to spread in the afternoon, Rudolf said.

Temperatures in the Czech Republic have been very high over the past few days, with new records broken on Monday for a July 25, and a maximum of 36.4 degrees Celsius (97.5 degrees Fahrenheit) recorded in the western Pilsen region.