A large wildfire in Wood River Valley, Idaho has burned approximately 100,000 acres since it began August 7.

Weather conditions on Friday and Saturday helped the large fire to grow even larger. Today’s cooler weather has been helping the firefighters to battle the wildfire.

Approximately 2,000 people have been evacuated. More people could be told to evacuate soon.

"Begin preparations now so that you can leave immediately should conditions deteriorate," the sheriff's office told CNN .

Fighting a fire as large as this one is very difficult. Firefighters have been working 12-hour shifts, and Governor Butch Otter called the National Guard to help fight the fire.

"We're [the National Guard] designed to go into austere locations and we're trained to survive. We have all that stuff lined up for us so it makes it easy for us to help out in those situations," Lt. Richard Wilson told local news station KTBV .

The fire, started by lightning, is still not completely contained.