A New Zealand firefighter, who spent several weeks battling one of the deadliest wildfires ever seen in California, says crews in Los Angeles are right now facing an impossible task.

It comes as America's second biggest city continues to be ravaged by ongoing catastrophic wildfires that have killed at least 10 and obliterated whole neighbourhoods.

Fire and Emergency's Northland district manager Wipari Henwood was one of dozens of New Zealand firefighters deployed in 2018 to help tackle a string of destructive wildfires in Northern California.

The Carr Fire, between July and August 2018, scorched about 93,000 hectares across the state's Shasta and Trinity counties, destroying more than a thousand homes.

Eight people were killed, including three firefighters.

The New Zealand crew of 34 was also tasked with bolstering firefighting efforts against the Mendocino Complex wildfires that burned for three months, searing about 186,000 hectares combined.

One firefighter was a further casualty in what turned out to be the most destructive wildfire season ever in California's history.

More than six years later, the Los Angeles County is now reeling with the Palisades Fire and the Eaton Fire already ranking as the most devastating in Los Angeles' history.

Henwood said there was little firefighters could do when faced with an "embers storm".