A dangerous heat dome that continues to smother much of the West intensifies this weekend with triple-digit thermometer readings expected for many western Montana valleys.

Beginning Friday, low-lying areas like Libby and Plains will endure four days of excessive heat warnings. A mercury-bursting high of 107 is possible Sunday in Libby, with 105 on Monday. The warning area encompasses all of Lincoln, Sanders and Mineral counties.

Meanwhile, a heat advisory is in place for Flathead County through July 24, with highs in Kalispell hitting 99 on Sunday and 98 Monday. Even parts of Glacier National Park will sizzle in the mid 90s.

While wildfire smoke could limit daytime heating, the National Weather Service in Missoula said with overnight lows remaining in the 60s and 70s it elected to issue the heat warnings and advisories.

"Heat safety for both humans and animals alike will be of utmost importance during this time and should not be taken lightly," the Weather Service warned in its Thursday forecast. "With the influence of smoke in the air around the region, degraded air quality will only add to the stress on the body during this time, and those with sensitivities to both heat and poor air quality should exercise special care to ensure they remain well."

Minimizing direct exposure to sun and reducing strenuous activity is advised.

THE PROLONGED heat wave has prompted elevated fire warnings for western Montana. Fire danger is rated as high on the Flathead Forest and very high on the Kootenai Forest.

Stage 2 restrictions go into effect Friday for portions of the Bitterroot and Lolo forests, and on the Flathead Reservation.

AccuWeather meteorologists warn there is a high risk for wildfires sparking through this weekend across the West, particularly in areas affected by dry lighting. According to an AccuWeather media release, more than 1,000 fires have been sparked by dry thunderstorms this year.

More than 50 large wildfires are burning in the U.S. this week, according to the National Interagency Fire Center, and more than 3 million acres have burned across the country so far this year. Multiple fires are also burning in western and central Canada.

Smoky and hazy skies could drift across the northern Rockies and continue pushing east in the coming days, according to AccuWeather.

Active fires in Montana include the Miller Peak incident south of Missoula. It was estimated at 2,035 acres on Thursday with no containment. More than 350 firefighters were working the blaze. An evacuation warning remained in place for portions of Upper Miller Creek Road. More than 480 structures are threatened by the fire, but so far none have been lost.

The Horse Gulch Fire near Helena was 32% contained at 14,250 acres on Thursday, while the lightning-caused Prairie Fire in southeast Montana was sized at nearly 40,000 acres.

Air quality Thursday afternoon was listed at moderate for the Flathead Valley.