The Wall Fire has burned 2,700 acres and is threatening at least 60 homes east of the Northern California city of Oroville.
The recent record-setting wet winter is helping and hindering firefighters' efforts.
The trees had plenty to drink in the last few months and the moisture helps them defend against fire. But several days of 100-degree plus heat is drying out every bit of low-lying vegetation in the area.
Jordan Motta is a CAL FIRE Captain.
"Fine grass fuels and brush out in the fire area are really combining with those high temperatures to help the fire to spread," says Motta.
The area has also had several fires in recent years and there are a lot downed or dead trees.
Air tankers have spent every hour of daylight flying from the Chico Airport 40 miles to the east to dump retardant on the fire's front lines.
Investigators have not identified a cause for the blaze.