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(LOS ANGELES) — Wildfires are continuing to spread in the West as more than 18 million Americans remain under heat alerts on the heels of a record-breaking heat wave.

The heat wave brought triple-digit temperatures to cities in Arizona, Utah, California and Montana and played a significant role in the rapid spread of fires over the weekend. Las Vegas tied its all-time high temperature at 117 degrees on Saturday, while temperatures in Death Valley reached 130 degrees on Friday.

While the heat wave is now easing, hot conditions will continue, spelling trouble for firefighters battling the blazes.

Dozens of large wildfires are currently burning in the West.

The Beckwourth Complex Fire in Doyle, California, has become the state’s largest wildfire of 2021 at more than 86,000 acres and is just 20% contained, according to the U.S. Forest Service. The fire prompted mandatory evacuations, closed portions of U.S. Route 395 and has nearly crossed state lines into Nevada, ABC Sacramento affiliate KXTV reported.

Another wildfire sparked in California overnight Sunday. The River Fire, located in Madera and Mariposa Counties, grew to more than 4,000 acres in just hours and is only 5% contained. Mandatory evacuations have been ordered for several neighborhoods in the vicinity.

The Bootleg Fire in Klamath County, Oregon, had spread to more than 153,000 acres by Monday, prompting evacuations in the area, according to the U.S. Forest Service. It was first spotted in the Fremont-Winema National Forest on July 6 but exploded to 75,000 acres on Saturday, ABC Portland affiliate KATU-TV reported.

Evacuations were also ordered due to the Rock Creek Fire in Craig, Montana, which shut down portions of Interstate 15.

Extreme drought and dry conditions are persisting, creating matchbox conditions for any spark to ignite into a fast-moving blaze.

The entire state of California is in drought and 85% is in extreme drought, while nearly two-thirds of Utah is in exceptional drought, and more than one-third of Washington state is in extreme drought, according to the U.S. Drought Monitor.

Some monsoon thunderstorms in the West also pose the risk of dry lightning sparking more fires.

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