Unstable weather to fuel Oregon blaze that is now larger than NYC

Dry, unstable and windy conditions are expected to continue fuelling a massive wildfire in the US state of Oregon, forecasters said, as firefighters battle the largely uncontained blaze that is now larger than the area of New York City.

More than 2,100 firefighters were again struggling to contain the vast Bootleg Fire raging in southern Oregon, near the border with California, while some were forced to retreat as the fire spread amid the fourth intense heatwave of the summer.

California, hit by its own wildfires, vowed to send firefighters to help out in Oregon.

An initial review on Friday showed the Bootleg Fire destroyed 67 homes and 117 outbuildings overnight in one county, while forcing 2,000 people to evacuate. Another 5,000 buildings, including homes and smaller structures in a rural area just north of the California border, are also threatened, fire spokeswoman Holly Krake said.

Active flames are surging along 322km (200 miles) of the fire’s perimeter, she said, and it is expected to merge with a smaller, but equally explosive fire by nightfall.

The Bootleg Fire is now 976 square kilometres (377 square miles) – larger than the area of New York City – and remains just seven percent controlled, according to the InciWeb website.

“(The) fire remains very active with significant acreage increases due to hot, dry, and breezy conditions,” the official site said.

“We’re likely going to continue to see fire growth over miles and miles of active fire line,” Krake said. “We are continuing to add thousands of acres a day, and it has the potential each day, looking forward into the weekend, to continue those three to four-mile runs.”

A red flag weather warning was issued for the area through Saturday night.

“We have had record heat, and just all the worst possible conditions at one time,” Suzanne Flory, a US Forest Service spokesperson, told the Oregonian newspaper.

Extreme heat and drought conditions have fuelled wildfires in the western United States and Canada in recent weeks – and stretched firefighting resources to their limits.

Canada is bringing in some 100 firefighters from Mexico to bolster their exhausted counterparts in northwestern Ontario, provincial authorities announced.

Canadian officials anticipate high temperatures in coming days from Alberta to Ontario – though nothing like the record 121 degrees Fahrenheit (49.6 degrees Celsius) recorded near Vancouver three weeks ago.

That heatwave contributed to hundreds of deaths in British Columbia alone, authorities said.

Meanwhile, air quality alerts were issued across four western Canadian provinces.

Scientists say the current heatwaves would have been “virtually impossible” without human-caused climate change.