San Francisco  - California firefighters gained the upper hand Monday on a rash of wildfires that have devastated the state for three weeks. But the problems continued in the Golden State as the violent thunderstorms that helped douse the flames also triggered mudslides.

"If it isn't fire, it's flood. If it isn't fire or flood, it's the mud," said Christina Lilienthal, an interagency fire spokeswoman after a huge mudslide hit an area that suffered wildfires last year that damaged about 50 homes. The National Weather Service issued a flash flood watch for Santa Barbara, Ventura and Los Angeles county mountain areas.

"Anywhere in the mountains that has experienced these burns in the past one to two years are most susceptible" to flooding with such rapid rainfall, said Jamie Meier, a meteorologist with the National Weather Service. "All of the topsoil and things are really loose right now because there has not been a lot of regrowth."

Across the state, 288 blazes were still burning Monday, with more than 21,200 firefighters still deployed to fight the flames. About 300 homes remained threatened in the Camp Fire, which razed some 50 houses and killed one person last week in the town of Concow some 150 kilometres north of the state capital of Sacramento. The fire was
55 per cent contained Monday.

Some 1,780 massive fires have burnt more than 3,300 square kilometres since they were sparked by a barrage of freak lightning storms on June 20 and June 21.

Firefighters from around the country have poured in to help California. More than 130 firefighters from Canada, Mexico, Greece, Australia and New Zealand are also helping.

The massive fires came after California experienced its driest spring since 1894, and accelerated the normal fire season by some two months. Traditionally the worst months for wildfires in California are in September and October when hot Santa Ana winds blow from the desert across southern California. (dpa)