Hundreds of firefighters scrambled today to contain three wildfires in drought-hit northern California that have scorched nearly 40,000 acres.

Among them is a popular tourist lake preparing to welcome hordes of visitors for the 4 July US bank holiday weekend.

Evacuation orders were in place along stretches of Shasta Lake - a camping and boating hotspot 160km south of the Oregon border - as soaring temperatures and high winds spur blazes at a relatively early stage in the region's fire season.

Around 40 structures were destroyed, including at least half a dozen homes near the town of Lakehead, an AFP photographer said.

"We were fully booked, but right now you can't get in even if you want to," said Cecil Hengst, owner of the Lakehead Campground and RV Park, forced to temporarily close by evacuation orders.

"This (fire) got really close... it's a bad one," said Mr Hengst, 63, who has been in the area for 12 years.

"Everything's so dry with the drought. We have had very little rain, our lake levels are so low right now for this time of year. It's perfect conditions for fires right now."

Further north, the larger Lava and Tennant fires continued to spread in mainly remote forested areas, sending up dense grey smoke plumes that blanketed much of the region.

Flames surround a drought-stricken Shasta Lake early this morning

The Lava Fire was sparked by lightning last week, and more than 500 further lightning strikes were recorded in California over the past 24 hours, threatening to prompt new blazes.

Dozens of fires are raging in western North America, from Canada to California, after a deadly heat wave that has largely begun to ease in recent days.

In Canada, around 1,000 people were moved to safety in British Columbia province yesterday when a wildfire burnt down 90% of a small town that had set a national high-temperature record for three days in a row.

Experts say the heat wave on "steroids" was brought on by the global climate change crisis and has caused several hundred deaths in Canada and the United States.

The town of Lytton, 250km northeast of Vancouver, "has sustained structural damage and 90% of the village is burned, including the centre of town," local MP Brad Vis said.

People enter Hillcrest Community Centre where they can cool off during the extreme hot weather in Vancouver

British Columbia has recorded 62 new fires in the past 24 hours, premier John Horgan told a press conference.

"I cannot stress enough how extreme the fire risk is at this time in almost every part of British Columbia," Mr Horgan said.

Lytton's 250 residents were evacuated on Wednesday evening, one day after it set a jaw-dropping Canadian record high temperature of 49.6C.

Firefighters are battling a number of wildfires across western Canada and the US
following soaring temperatures

The evacuation order was extended that night to residents of about 100 properties north of Lytton.

"The last 24 hours have been devastating for Lytton residents," Defence Minister Harjit Sajjan said, adding that the Canadian armed forces "are ready to support residents as we move forward in the next steps."

Provincial authorities have not yet announced any injuries or deaths related to the fires. A number of the blazes were clustered north of the city of Kamloops, located about 150km northeast of Lytton.

Environment Canada said in a bulletin issued early yesterday for the Prince George, BC area saying that "an exceptionally strong ridge of high pressure over British Columbia will continue to bring record-breaking temperatures over the next couple of days."

People rest at the Oregon Convention Center cooling station in Portland

"The duration of this heat wave is concerning as there is little relief at night with elevated overnight temperatures," it added.

The heat wave has continued to move eastward into the central Canadian prairies.

In addition to British Columbia, heat warnings have been issued for the provinces of Alberta, Saskatchewan, Manitoba, and parts of the Northwest Territories, and now northern Ontario.

Across the border, the US states of Washington and Oregon have also been sweltering under record temperatures this week and several hundred sudden deaths have been reported.