Smoke is beginning to mix and move eastward from the Interstate-5 corridor as winds pick up across the Northwest. Air quality is expected to improve for many closer to the coast, but there is some concern of additional fire spread as we move toward the weekend.

Here's where the fires are burning

The most numerous large wildfires right now are burning in the eastern two-thirds of Oregon and Washington.

Three of those burning in the Spokane, Washington, metro area destroyed hundreds of homes and businesses. Thirty large fires are burning in central and eastern Oregon.

Other large fires are burning in Idaho, Montana and Utah, among other western states.

(The Weather Company Labs: Active wildfires and fire weather tracker)

Where the smoke will go

Winds are slowly increasing from the Pacific across Washington and Oregon. A gradual lifting of the smoke that has lingered since earlier in the week is expected Friday west of the Cascades and a more rapid push of these winds will mix out smoke across the Northwest as we move into the weekend.

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Air quality should see a rapid improvement in Seattle and Portland on Friday.

Smoke will remain locally dense close to the fires in the lowlands of eastern Washington and Oregon.

This smoke will spill across the Rockies late week. Not a great time to head to Yellowstone or Aspen.

Ground smoke will also continue in Boise and could flow as far south as Salt Lake City.

(MORE: Fire suspect was questioned in 2 earlier blazes)

Temperatures expected to drop

Afternoon temperatures will drop some 5-10 degrees between Thursday and Sunday and the threat of record highs will be much lower going into the weekend.

This will decrease the threat of new fires, but an increase in wind gusts could spread already existing fires eastward. Some gusts could exceed 30 mph in the lower elevations, likely peaking on Saturday or Sunday.

The same Pacific air that will push smoke inland over the West will also cool the Olympic Peninsula and much of the coast of Washington and Oregon into the 70s and 80s.

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What you need to know to stay safe

Wildfire smoke is hazardous to breathe for several reasons.

It contains microscopic particulate matter much smaller than the width of a human hair that can lodge deep into the lungs and then enter your bloodstream.

It can lead to short-term effects, such as coughing, shortness of breath, a scratchy throat, runny nose and burning eyes.

Prolonged exposure to dense smoke can increase the risk of chronic lung issues and increase inflammation that could lead to heart attacks and strokes.

(MORE: What's really in wildfire smoke?)

Check your air quality forecast before heading outside.

You can do that on The Weather Channel app by going to your local forecast, then tapping the "Breathing" button. Or, from your local forecast page on weather.com, click on the "Air Quality" button at the top.

The index is color-coded from green (good) to maroon (hazardous).

If your air quality forecast is:

• At least code orange: More sensitive groups such as those with respiratory or heart conditions, the elderly, children and those pregnant should avoid staying outside more than necessary.
• Code red, purple or maroon: Everyone should limit their time outdoors. Consider exercising indoors and if you need to walk your pet outside, do so as briefly as possible.

(MORE: Wildfire smoke myths)

Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. Extreme and bizarre weather are his favorite topics. Reach out to him on Bluesky, X (formerly Twitter) and Facebook.​