KUSA — A fire that started burning northwest of Fort Collins Tuesday afternoon has now grown to 139 acres and is threatening 11 structures.

U.S. Forest Service spokesperson Katherine Armstrong said Wednesday that the fire near Seaman Reservoir is now within a half mile of those structures, which are under a voluntary evacuation.

The fire was sparked by lightning Tuesday afternoon. Multiple fire crews are now responding and air support was called in that same day.

Temperatures are supposed to reach record highs on Wednesday, with warm weather continuing into early next week.