A wave of extreme heat has affected areas of the United States, home to tens of millions, with record temperatures expected in the central and northeastern parts of the country and wildfires raging in California, AFP and Associated Press reported.

The fire, dubbed the Oak Fire, is one of California's largest of the year.

It started on Friday near Yosemite National Park, where there are giant sequoias.

The fire has now spread over 26.5 square kilometers, destroying and damaging buildings, the California Forestry and Fire Protection Service announced yesterday.

Fire threatens giant sequoias in California

Roads were cut and several areas with a population of more than 6,000 were ordered to evacuate.

About 400 firefighters are fighting the flames with the help of bulldozers, helicopters and other aircraft, but so far the "Oak Fire" has not been brought under control, notes BTA.

The fire spread in almost all directions because of the presence of a lot of flammable materials and the extreme drought, emphasizes climatologist Daniel Swain of the University of California.

Boston Mayor Michelle Wu declared a "heat emergency."

The temperature is expected to reach 37 degrees today.


Forest fires