Isolated showers and thunderstorms forecast for Sunday through Monday evening may spark fires and create conditions to spur explosive growth.
The National Weather Service in Boise issued red flag warnings for the areas from around McCall to the southern border of the state, including the Treasure Valley.
Conditions such as strong winds, low humidity and warm temperatures feed the growth of fires.
Sunday's temperatures were expected to reach a high of 100. Monday's high could reach 101.
Tuesday should be clear and hot with temperatures reaching 97 degrees.