The wildfire smoke is back, filling skies as far south as Florida

Smoke from dozens of fires burning across Oregon, Washington and British Columbia is pouring across the United States and Canada.

It will cause hazy skies and reduce air quality in some areas this week.

Some of the smoke will reach as far south as Florida and the Gulf Coast on Monday, wafting across a 2,500-mile path that includes the Plains, Midwest and East.

“The extraordinary wildfire outbreak across Oregon, eastern Washington, and southern British Columbia has become even more alarming amid critical fire weather conditions,” climate scientist Daniel Swain wrote on Saturday.

Unlike the smoke outbreak in the East two weeks ago, most of it will remain high in the sky and not affect air quality. However, the hazy conditions could hold daytime high temperatures down by a few degrees.

Meanwhile, poor air quality from smoke across eastern Oregon, Idaho and Montana will spread into the central U.S. on Monday, as smoke also settles near the ground across parts of the Dakotas, Minnesota, Iowa and Nebraska. This surface smoke could continue to seep south and east on Tuesday, with light concentrations reaching other parts of the Plains and Midwest.

In Canada, air quality will be reduced in parts of eastern British Columbia, Alberta and Saskatchewan.

With a heat dome pivoting from the southern Plains to the Desert Southwest this week, clockwise winds around its periphery will continue funneling smoke from the Northwest toward the East Coast. Because of that, hazy skies will probably linger for some time to come — although smoke concentrations will ebb and flow from day to day.

The smoke is mostly coming from Oregon and Washington, where 52 uncontained and large fires were burning Sunday, according to the National Interagency Fire Center. Five large fires had broken out over the past day.

In total, these fires had burned through more than 1.1 million acres.

Four out of the five largest active fires in the country were in Oregon, with the fifth in Washington. Of these five, three were exhibiting extreme fire behavior.

In British Columbia, 26 uncontained and large fires had burned through more than 400,000 acres as of Sunday. In Canada, warmer fire seasons tend to be associated with more land burned.

Warming matters for fire because hotter air is thirstier. As temperatures rise, the air draws more water out of trees, grasses and other vegetation, drying them out and making it easier for wildfires to start and spread.

“This wildfire outbreak follows a 6-month sequence of historic winter warmth/extreme low snowpack driving severe drought, followed by lightning, then heat, then more lightning, then strong winds. Fires are currently almost too numerous to count, and evacuations are numerous,” Swain wrote.

He also noted that fire weather would probably ease slightly in the days ahead, but that more heat and lightning is expected by early August — and widespread rain is not.

“Today in Central Oregon, I met with firefighters and emergency response partners working on the front lines. I am deeply grateful for their courage and service, and I am committed to doing all I can to support their work,” Oregon Gov. Tina Kotek (D) wrote on Friday.

Since July 18, the national wildland fire preparedness level has been at 5 — the highest on the Interagency Fire Center’s scale — which can require “emergency measures” to sustain operations.