Tens of millions in US under extreme heat advisories, with record temperatures expected

About 125 million under heat alerts nationwide as firefighters battle blazes

A construction worker takes a water break in Folsom, California. Bloomberg

Dangerously hot conditions will dominate the rest of the long Independence Day weekend across much of the US West Coast, south-east and Middle Atlantic seaboard, forecasters said on Friday, as California firefighters battled one of the first big wildfires of the season.

About 125 million were under heat alerts nationwide, with more than 100 million under excessive heat advisories for the weekend.

Record-breaking temperatures were forecast for many spots in California, southern Oregon and the south-west, the National Weather Service said, with Death Valley facing the possibility of approaching its hottest-ever temperature of 56.6°C, set in 1913.

Parts of the western part of the country were expected to reach about 43°C on Friday, with some of the highest temperatures to be found in Phoenix, Arizona – the hottest large US city – which could hit 46°C, and Palm Springs, California, where the mercury could reach 48°C.

“Confidence is increasing that this potentially historic heatwave will last several days,” the National Weather Service in Portland said on X, adding that the risk of heat-related illness will increase significantly.

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 East Coast to Pennsylvania, where temperatures will reach past 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”.

Extreme heat is one of the leading weather-related killers in the US, leaving hundreds of people dead each year, according to the National Weather Service.

A 69-year-old man died due to heat-related issues in San Jose, California, this week, while a 10-year-old died in Arizona after experiencing a heat-related emergency while hiking with family.

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.

Wildfires

Hot, dry and windy conditions in the West were forcing fire officials and forecasters to issue warnings about the risk of wildfires.

Flames from the French Fire burn on a hillside above Mariposa, California. AP

The extreme heat, along with gusting winds and low humidity, means any fires that start are likely to spread quickly through already parched vegetation.

The so-called Thompson Fire in Butte County, California, about 105km north of Sacramento, has scorched almost 16km of scrub and brush since it started on Tuesday.

As of Friday morning, the fire was 46 per cent contained after forcing some 13,000 households to evacuate.

Fifty-nine wildfires have burnt almost 1,900 square kilometres acres in nine states, according to the National Interagency Fire Centre.

Twenty-one wildfires are being managed under full suppression strategies, with Alaska continuing to have the most activity, with 39 large fires.