U.S. weather experts have put much of the nation's southwest under “red flag” fire warnings, meaning that weather conditions in at least seven states are ideal for the start or spread of wildfires.

The National Weather Service said Sunday that high heat, low humidity and strong winds will make the battle to control existing wildfires in Arizona, New Mexico and Texas much more difficult.

Other states with areas under the red flag warning are Oklahoma, Colorado, Kansas and Utah.

Federal experts say there are 36 uncontained large fires burning around the nation. Of those, the worst is the “Wallow” fire in Arizona, which covers more than 200,000 hectares. Residents of several small towns have been ordered to evacuate.

Fire experts say that blaze is around 40 percent contained.