July 20 (UPI) -- As dozens of large wildfires burn across the Western United States, drought, severe heat and thunderstorms could make them harder to fight -- particularly the Bootleg Fire in Oregon, which has blackened more than 380,000 acres.
The National Interagency Fire Center said fires are burning across 13 states and have burned 1.29 million acres of land. The National Preparedness Level was at Level 5 Tuesday.
"This afternoon, isolated to scattered wet and dry thunderstorms are expected across eastern Oregon and Washington, Idaho, western Montana, and northwest Wyoming. Some of the storms will be capable of strong wind gusts and brief heavy rain," the NIFC said in a statement.
Among the worst-hit places were south-central Idaho, Northern California, the northern Rockies and south-central Oregon.
The Bootleg Fire grew by more than 20,000 acres from Monday to early Tuesday and was about 388,359, the U.S Forest Service said. Containment was 30%, but it's so large that it's creating its own weather.
Extreme heat from the fire has forced air to rise rapidly, creating thunderstorms with lightning and strong winds. Clouds have formed in several areas of the fire, according to the Lake County Sheriff's Office.
The National Weather Service issued red-flag warnings and excessive heat warnings, as well as fire watches for Idaho, Oregon, Nevada and Montana.
Montana currently has 18 active fires and Idaho has 17. California, Oregon and Washington state have nine, eight, and seven respectively.
The Bootleg Fire is the third-largest fire in state history and presently the largest burning in the United States. It began on July 6 in the Fremont-Winema National Forest near the California border and has forced more than 2,000 people to evacuate their homes. It's destroyed 67 homes.