After a somewhat subdued start, the fire season in Canada has suddenly come alive with a recent flare-up of blazes reminiscent of last summer, the country’s worst fire season on record. Concern is growing that the current explosion of fire activity could send at least some smoke south toward the United States.

Fast-moving fires, ignited by a lightning barrage, have swept over parched lands in western Canada desiccated by drought. Alberta and neighboring British Columbia have been hardest hit.

The national preparedness level, which signals the resources required to combat ongoing blazes, was raised to a Level 5 out of 5 on Monday.

“Potential for emerging significant wildland fires is high to extreme and expected to remain so in one or multiple agencies,” the Canadian Interagency Forest Fire Center wrote. “National availability of resources is limited, international resources are being mobilized.”

On average, fires burn more than 5 million acres per year. This year’s tally is closing in on 4 million acres and appears poised to exceed the average, perhaps by a wide margin. Fire season runs through at least September in much of the country. Last year, over 42 million acres were torched, driving massive plumes of smoke that infiltrated the United States.

One of the biggest eruptions of thick smoke from the fires this year is beginning to drift south. At least some will cross the U.S. border.

WHY FIRES ARE ERUPTING NOW

As of late June, significant levels of drought had developed in parts of British Columbia, Alberta and the Northwest Territories. Smaller areas of drought or unusually dry conditions were also present across the eastern half of the country, including parts of Labrador and Newfoundland.

While the drought is less extensive and intense than last year, many regions have seen a prolonged lack of precipitation. Large fires have started near the same areas they did a year ago.

Significant heat has also visited Canada’s west recently, and more is in the forecast.

Several locations in the Northwest Territories set all-time highs on Wednesday, according to Vancouver weather historian Thierry Goose. Yellowknife reached 90.9 degrees Fahrenheit while Hanbury River hit 93.2 degrees. In British Columbia, a handful of locations continued to bake at or above 104 degrees.

WHERE THE BIGGEST FIRES ARE BURNING

Alberta is near the epicenter of the fires. As of Wednesday, the government there reported 136 ongoing wildfires, with four being “of note.” Northeastern portions of the province are also blanketed in unhealthy-to-hazardous air as smoke fills the skies.

Some of the fire complexes in Alberta have scorched nearly 300,000 acres.

British Columbia reports 176 active wildfires, largely in the remote north near the border with Alberta. Some have forced evacuations. Significant blazes are also ongoing west of Edmonton and northwest of Calgary, which may impact their air quality.

Another 96 wildfires are burning in Saskatchewan, mainly in the wooded north-central portion of the province.

In Atlantic Canada, fires in Newfoundland and Labrador have diminished recently. This comes after a major fire threatened parts of Labrador City, about 600 miles north-northeast of Montreal, causing thousands to evacuate last week.

POTENTIAL SMOKE FOR THE U.S.

A shift in the weather pattern across North America will place a dip in the jet stream in the central to eastern United States over much of the next week or so.

Such a setup will allow steering currents to blow smoke from the region from British Columbia to Saskatchewan southeast toward the Midwest and Great Lakes. Some smoke could eventually be pushed toward the Northeast United States.

How thick or long-lasting the smoke may be is unclear, although there are already some hints of it in southern Canada and the northern tier of the United States.

In addition to the fires in Canada, several large wildfires in the Pacific Northwest are contributing smoke through that area and to the east. The largest fires are burning east of the spine of the Cascades in Washington and Oregon.