Wildfires are raging in the west of the United States as the region is hit by a heatwave that has brought record temperatures to several areas.

Communities have been told to evacuate as firefighters struggle to battle the blazes in the extreme conditions.

Las Vegas matched its all-time temperature high of 47.2C (117F), and California's Death Valley registered 54.4C (130F).

It comes just weeks after another dangerous heatwave hit North America.

The region experienced its hottest June on record, according to the EU's Earth observation programme.

Experts say that climate change is expected to increase the frequency of extreme weather events, such as heatwaves. But linking any single event to global warming is complicated.

However, a study by climate researchers said the heat that scorched western Canada and the US at the end of June was "virtually impossible" without climate change.

What is happening with the fires?

Firefighters battling the many wildfires in the region say the air is so dry that much of the water dropped by aircraft to quell the flames evaporates before it reaches the ground.

In the north of Nevada, near the border with California, people were evacuated from their homes as wildfires triggered by lightning strikes tore through parts of the Sierra Nevada forest region.

"As long as it's this hot and we have these low humidities, it's kind of hard to tell when and where we're going to catch this," Lisa Cox, information officer for the so-called Beckwourth Complex fires, told the Los Angeles Times newspaper.

In Oregon, a wildfire fanned by strong winds in the Fremont-Winema National Forest doubled in size to 120 sq miles (311 sq km) on Saturday.

The fire was threatening power cables that send electricity to California. Power grid operators in California have urged customers to conserve electricity by reducing their use of appliances and to keep thermostats higher during the evening when solar energy is diminished or no longer available.

In Idaho, Governor Brad Little declared a wildfire emergency on Friday and mobilised the state's National Guard to help fight fires also sparked by lightning.

Two firefighters battling a blaze in Arizona died on Saturday after their aircraft crashed, officials said. 

What about the heat?

Several areas in Nevada and California have matched or passed temperature records, according to preliminary data by the National Weather Service (NWS), and the extreme heat is expected to continue. 

The temperature recorded in Death Valley on Friday matched one recorded in August 2020 - which some argue is the highest temperature ever reliably recorded on Earth. A temperature of 56.7C (134F) was registered in the area in 1913, but this is contested by climate experts.

Millions of people are under an excessive heat warning, with those affected urged to drink plenty of water and stay in air-conditioned buildings where possible.

Cooling centres - air-conditioned public spaces - have been set up in some areas to help residents get relief from the heatwave.

Heat warnings have also been issued in parts of Canada, with those affected urged to consider rescheduling outdoor activities for cooler periods of the day, and monitor for symptoms of heat stroke or heat exhaustion.

The heat is not expected to reach the level seen in Canada at the end of last month when the village of Lytton in British Columbia reached 49.6C (121F) - breaking the country's highest recorded temperature.

The heatwave in June saw spikes in sudden deaths and increases in hospital visits for heat-related illnesses. Hundreds of deaths were recorded in British Columbia.