A record-shattering heat wave has triggered a spate of massive wildfires across British Columbia and the American West, with one blaze roaring through parts of Lytton, Canada on Wednesday night. This occurred just a day after the town set a national high temperature record of 121°F.

Why it matters: The unprecedented heat is leading to other deadly threats as residents hastily evacuate areas in the path of quickly-advancing flames, including deteriorating air quality.

• Climate change plays a key role in heightening the severity of both heat waves and wildfires.

Driving the news: The long-lasting heat wave has toppled dozens of all-time temperature records across the Pacific Northwest and British Columbia — the result of an unusually powerful area of high pressure, colloquially known as a "heat dome," sitting over the region and forcing air to stagnate.

• The extreme heat, which climate scientists say would have been virtually impossible to achieve without human-caused global warming, helped dry out soils further in an area that was already unusually parched for this time of year, leading to dangerous wildfire conditions.

Zoom in: Based on news reports, satellite imagery and social media posts, at least parts of Lytton, British Columbia, were seriously damaged when the Spark Fire erupted, quickly expanded in size and swept into the community late Wednesday and into Thursday.

• According to CBC News, the town's approximately 250 residents were given a mandatory evacuation order at 6 p.m. local time Wednesday, but the fire moved swiftly across the community. People were evacuating while homes and businesses were burning.
• This led to scenes reminiscent of the past few horrific fire seasons in California, with people fleeing past burning homes and cars on the side of the road.
• Lytton, about 150 miles northeast of Vancouver, received international headlines when it set all-time national heat records on three straight days, culminating in the 121°F reading on Tuesday.

Wildfires are also burning in Northern California, where drought and heat has left forests fire-prone far earlier in the fire season than usual. In fact, the entire western U.S. is mired in drought conditions, and the wildfire threat this season is so severe it was the subject of a White House summit on Wednesday.

Details: The heat wave is the worst on record to hit the Pacific Northwest, British Columbia, and the Northwest Territories. One location in the Northwest Territories reached a high temperature of 103°F on Wednesday, the hottest on record for any location above 60 degrees North.

• More than a dozen large blazes erupted on Wednesday across British Columbia, northern California, and other parts of the West, touched off by erratic winds, high heat, and dry, combustible vegetation.

I've watched a lot of wildfire-associated pyroconvective events during the satellite era, and I think this might be the singularly most extreme I've ever seen. This is a literal firestorm, producing *thousands* of lightning strikes and almost certainly countless new fires. #BCwxhttps://t.co/jS0DrJldR3

— Daniel Swain (@Weather_West) July 1, 2021

• Smoke plumes from these fires reached 55,000 feet into the air, and helped manufacture their own weather. At least one storm generated a severe thunderstorm warning due to the severity of its associated smoke cloud, which from the ground resembled an explosion.
• One meteorologist who tracks lightning activity noted about 710,000 lightning events in British Columbia and Alberta on Wednesday, about 0.2% of all of Canada's lightning activity in an entire year.
• These pyro-cumulonimbus clouds reminded weather researchers of those that grew out of the devastating wildfires in Australia in 2019 to 2020.

By the numbers: The death toll from the heat wave itself has risen into the hundreds in Canada alone, with dozens dead in the U.S. as well.

• On Wednesday, British Columbia's chief coroner reported about 500 heat-related deaths so far, but this number may rise in coming days. About 60 heat-related deaths have been recorded in Oregon, as well.
• The heat wave set all-time highs in Portland, Ore., at 116°F and Seattle, at 108°F, among other locations. Both Oregon and Washington may have tied or set all-time state records.
• Excessive heat warnings remain in place in parts of the Northwest, and the heat continues in parts of Canada as well.

Go deeper: Pacific Northwest heat wave, Canada temperature record shock experts