Strong, dry winds are fuelling fires in Los Angeles and making it difficult for firefighters to battle them.

Officials urged residents to be prepared to evacuate at any time as the winds are expected to continue until Thursday afternoon.

The fires over the past few days have consumed an area roughly the size of Washington, D.C. At least 25 people have died so far and about 6.5 million people are still under threat from the fires, which have destroyed more than 12,000 homes and buildings and displaced 200,000 people.

Some 82,400 people have been ordered to evacuate and a further 90,400 are under evacuation warnings.

About 8,500 firefighters from the western United States, Canada and Mexico were able to control the growth of the fires for three days.

The Palisades Fire on the western edge of the city was 19 per cent contained and the Eaton Fire in the foothills east of the city was 45 per cent contained.