MOSES LAKE — Washington's three largest wildfires have burned more than 390,000 acres and continue to challenge firefighters as smoke from the blazes is expected to push air quality across much of central Washington into unhealthy and very unhealthy levels this week. 

The largest of the fires, the Sinlahekin Fire in Okanogan County, has burned 141,411 acres since lightning sparked the blaze July 26. The fire was 42% contained Monday, with approximately 1,560 personnel assigned to the incident, according to InciWeb.  

Fire managers said several portions of the fire remain active as crews continue building and reinforcing containment lines. Officials described fire behavior as unusually intense for early August, with fuels burning under conditions more typical of late summer. While some evacuation orders have been reduced, authorities warned residents returning to affected areas to remain prepared for rapidly changing conditions. 

The fire is estimated to have cost $50 million so far, according to the National Interagency Fire Center.  

Just south of the Sinlahekin Fire, the Kaiser Canyon Fire has scorched 138,213 acres on and around the Colville Reservation near Nespelem. The lightning-caused fire, which began July 16, is now 63% contained, according to InciWeb.  

Firefighters continued suppression efforts along the northwest flank of the fire near Moses Mountain on Monday, while crews worked to strengthen containment lines and mop up hot spots in less active areas. Fire managers said burning remains active in large dead trees and downed timber, with grass and brush continuing to carry fire spread in some areas. 

The Kaiser Canyon Fire has drawn 966 personnel and carries an estimated suppression cost of $60 million, according to NIFC.  

The state's third-largest blaze, the Little Giant Fire in Chelan County, remains the most difficult to contain. The fire has burned 111,429 acres since July 15 and is just 2% contained, according to InciWeb.  

Officials reported significant fire growth over the weekend in the Entiat River Valley, where multiple smoke columns developed, including one that reached approximately 20,000 feet into the atmosphere. The fire threatens nearly 2,000 structures and has prompted a massive firefighting response that includes 1,734 personnel, 41 hand crews, 75 engines, 28 bulldozers and five helicopters. 

Fire managers said full suppression efforts remain underway as crews prioritize the protection of life and property. 

The Little Giant Fire is also estimated to have cost $60 million, according to NIFC. 

Together, the three fires account for nearly 391,000 acres burned, making them the dominant wildfire incidents in Washington and major contributors to deteriorating air quality across the region. 

The smoke impact is already being felt. Air quality readings Monday reached 174 in Coulee City, Ephrata and Soap Lake, placing those communities in the "Unhealthy" category. Moses Lake and Warden recorded readings of 59, while Othello measured 62 and Ritzville 64, all within the moderate range. 

Air quality forecasts show conditions worsening substantially through the week, according to AirNow.  

By Wednesday, forecasters expect Very Unhealthy air quality in Coulee City, Ephrata, Moses Lake, Ritzville, Soap Lake and Warden. Othello is forecast to reach the Unhealthy category Wednesday before deteriorating to Very Unhealthy conditions Thursday and Friday. 

An Air Quality Index between 201 and 300 is considered Very Unhealthy, meaning everyone may experience health effects. Health officials recommend people stay indoors as much as possible, keep windows and doors closed, use filtered air when available and avoid strenuous outdoor activity. Sensitive groups, including children, older adults and those with heart or lung conditions, are urged to avoid all outdoor exertion during those conditions. 

Fire officials said cooler temperatures and slightly higher humidity are expected early this week, but periods of wind and the potential for thunderstorms later in the week could continue to influence fire behavior and smoke production across the region. 

Active blazes in Washington: 

Border 2 Fire: 10,582 acres. No containment. Started on July 16. Whatcom County. Lightning caused. The total estimated cost is $1.96 million.  

Bradeen Hill Fire: 4,419 acres. 74% containment. Started on July 25. Stevens County. Human caused. The total estimated cost is $14.9 million. 

Grant Park 2 Fire: 200 acres. No containment. Started on Aug. 7. Pierce County. Unknown cause. The total estimated cost is $500,000. 

Hugh Lava Fire: 874 acres. No containment. Started on July 23. Skamania County. Lightning or natural cause. The total estimated cost is $3 million.  

Hudspeth Fire: 6,635 acres. 32% contained. Started on Aug. 1. Stevens County. Unknown cause. The total estimated cost is $4.9 million.  

Kaiser Canyon Fire: 138,235 acres. 63% contained. Started on July 16. Okanogan County. Lighting caused. The total estimated cost is $60 million.  

Little Giant Fire: 111,429 acres. 2% containment. Started on July 15. Chelan County. Lightning caused. The total estimated cost is $60 million.  

Luna Fire: 3,583 acres. No containment. Started on July 24. Whatcom County. Unknown cause. The total estimated cost is $5 million.  

Mitre Rock Fire: 4,518 acres. 94% contained. Started on Aug. 1. Stevens County. Unknown cause. The total estimated cost is $12 million.  

Modrite Fire: 57,154 acres. 61% contained. Started on July 17. Ferry County. Lightning or natural caused. The total estimated cost is $50 million.   

Palouse River Fire: 637 acres. No containment. Started on Aug. 8. Whitman County. Unknown cause. The total estimated cost is unknown.

Ptarmigan Fire: 23,467 acres. 8% contained. Started  on July 17. Okanogan County. Lightning or natural caused. The total estimated cost is $5 million. 

Sinlahekin Fire: 141,411 acres. 42% contained. Started  on July 26. Okanogan County. Lightning or natural caused. The total estimated cost is $50 million.  

Skyo Fire: 254 acres. 83% contained. Started on July 22. Lewis County. Lightning caused. The total estimated cost is $6 million.  

Spokane Area Fires: 9,944 acres total. Old Trails fire is 53 percent contained. Fairview Fire is 53% contained. Autumn Lane Fire is 73 percent contained. Started on Aug. 1. Spokane County. Human caused. The total estimated cost is $23 million.  

Three Queens Fire: 2,000 acres. No containment. Started on July 15. Kittitas County. Lightning or natural caused. The total estimated cost is $20 million.  

Well Road Fire: 1,812 acres. No containment. Started Aug. 8. Whitman County. Unknown cause. The total estimated cost is $300,000. 

SOURCES: INCIWEB, NATIONAL INTERAGENCY FIRE CENTER and AIRNOW.