The fire was reported just after 6 p.m. Saturday along Highway 173.
Since then, the fire nearly tripled in size - jumping from 300 acres to 1,078.
Evacuation warnings include homes in the Arrowhead Equestrian Estates area.
By Sunday evening, the fire was 20% contained.
Firefighters continue to battle the blaze from the ground and the air.
UPDATED: An earlier version of this story said the fire had grown to more than 1,300 acres. Fire officials later issued a revised, lower estimate of the size.