A wildfire in California has become the largest in the state’s history, as several uncontrolled blazes cause damage to homes and businesses amid record-breaking summer temperatures.

The Mendocino Complex fire, which started late last month, has burned more than 120,000 hectares and destroyed more than 250 structures. US news reports say it may not be contained until next month.

The Carr fire, near Redding in the state’s north, has burned 72,000 hectares and has destroyed 1077 homes, 22 commercial structures and 500 outbuildings.

In southern California $US800 million ($1.1 billion) of commercial structures are threatened by the Holy Fire, the Federal Emergency Management Agency says.

Fires have also affected tourism centres, with parts of Yosemite National Park closed for more than two weeks.

More than 13,000 firefighters from California, 17 other US states, Australia and New Zealand are in action as high-risk weather conditions continue.

The National Oceanic and Atmospheric Administration says California experienced its hottest July and hottest month on record, while the US had its warmest May-July period.

Moody’s estimates insurance losses from the Carr fire alone likely reached $US1.5 billion ($2 billion) early this month.

Losses from Californian fires in October and December last year reached nearly $US12 billion ($16 billion).