Fanned by strong winds, the wildfires have killed at least 24 people and swept through 40,000 acres in the Greater Los Angeles area.

"We are not out of the woods yet. Please stay on guard for a fast-moving fire," the weather service's Los Angeles office warned.

The threat of powerful wind gusts combined with bone-dry humidity in Los Angeles on Wednesday could pose a severe test for firefighters who have been battling to keep monstrous fires in check since last week.