(CNN)There are currently 80 large wildfires raging in 13 states across the US, burning more than 1 million acres, mostly in western states, according to the National Interagency Fire Center (NIFC).
80 large fires have consumed more than 1 million acres across western parts of the US
Montana has reported the most large wildfires with 18, and Idaho is close behind with 17, the NIFC said. In addition to wildfires, parts of Idaho and Montana are also seeing a heatwave that has brought above-average temperatures, according to the National Weather Service (NWS).
NWS tweeted a map Sunday showing triple-digit temperatures in the region.
"These hot temperatures will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. Car interiors will reach lethal temperatures in a matter of minutes," NWS Great Falls tweeted.
High temperatures are expected to reach 103 degrees in Montana and 102 degrees in parts of Idaho. The NWS has issued an excessive heat warning for eastern Montana and a heat advisory for the state's central region.
A heat advisory has also been issued for southeastern Idaho. A red flag warning is in effect for southwestern Idaho and eastern Oregon, which means "critical fire weather conditions are either occurring now, or will shortly," according to the NWS.
Those conditions are contributing to the Bootleg Fire burning in the Fremont-Winema National Forest along the Oregon and California border. It has grown to 298,662 acres as of Sunday afternoon, according to data from InciWeb, the US clearinghouse for wildfire information. The fire has burned the most acres of all the active wildfires, according to CNN Meteorologist Gene Norman.
The Bootleg Fire, which began July 6, is now 22% contained and has destroyed at least 75 structures, including 21 homes, and threatens an additional 5,072 homes, according to Marcus Kaufman, Bootleg Fire spokesperson.
Near the California-Nevada border, the Tamarack Fire has grown to 18,299 acres as of Sunday and is 0% contained, according to information from InciWeb.
The fire was sparked by lightning near the Alpine County, California, community of Markleeville on July 4, and has triggered mandatory evacuations for a number of campgrounds and neighborhoods in the area.
The fire has also burned at least three structures and jumped Highway 89 at one point on Saturday, according to InciWeb.
The fire danger will persist across the western US Monday, Norman said, as a combination of dry thunderstorms and excessive heat.