Firefighters reported significant gains on Wednesday against the two massive wildfires burning around Los Angeles, while also extinguishing smaller blazes set by arsonists in recent days as a final round of windy, flame-fanning weather moved through Southern California.

A Particularly Dangerous Situation red-flag warning expired in the afternoon, but dry conditions and gusty winds were forecast to linger into Thursday.

So much of the nation’s second-most populous metropolitan region remained on alert for new outbreaks and flare-ups from the fires, which have killed at least 25 people and destroyed thousands of homes.

Earlier on Wednesday, gusts whipped up to 80 kph in the mountains, though many areas saw relatively light winds late in the morning, according to the National Weather Service.

Better conditions expected in the coming days should help fire crews make even more headway and allow residents to return to their neighbourhoods to begin rebuilding.

Still, firefighters and police faced new challenges. Since the beginning of the wildfire outbreak last week, authorities have arrested about half a dozen people accused of setting new, small fires that were quickly knocked down.

Authorities have not determined a cause for the major blazes in what is on track to become the nation’s costliest fire disaster.

More manageable winds on Tuesday allowed firefighters to make gains on the two most destructive fires. Almost half of the Eaton Fire just north of LA was contained, and one-fifth of the fire that destroyed much of the seaside neighbourhood of Pacific Palisades was surrounded.

Both of those broke out on January 7. (AP)