SACRAMENTO (REUTERS) - Hot, dry conditions and intense winds across California are threatening to reinvigorate what has already been the worst fire season in state history, officials warned on Tuesday (Oct 13).

Gusty winds in California's north and extreme heat in its south are creating conditions that could fan wildfires that began earlier in the summer as well as spark new ones, leading state and federal authorities to urge residents to prepare.

The National Weather Service issued a heat advisory for a wide swath of Southern California as temperatures topped 32 deg C.

The agency asked residents to exercise caution with any fire sources.

The California Department of Forestry and Fire Protection (Cal Fire) said strong winds and low humidity could ramp up blazes in Northern California starting Wednesday.

"While good progress has been made on a number of fires, this could hamper containment efforts," Mr Daniel Berlant, Cal Fire assistant deputy director, said on Twitter on Tuesday.

"It means if a new fire breaks out, that that fire is going to be able to burn very rapidly."

Pacific Gas and Electric Company (PG&E), which provides power to much of California, said Monday it was considering proactively shutting off power as soon as Wednesday to as many as 50,000 state residents to mitigate fire risk.

This year, wildfires have burned over 1.6 million hectares in California - twice the total of 2018 which had been the highest on record. Five of the six largest fires in state history were in 2020. Thirty-one people have died, and over 9,200 structures have been destroyed.

Autumn has tended to be California's peak wildfire season, but state officials say the season is growing longer each year.

Experts say droughts and climate change from fossil fuels have made poorly managed forests much more flammable, leading to extreme fire activity.