California firefighters on Monday tackled the state's biggest blaze of the year so far, as fears intensify over ominous conditions forecast for the hot, dry months ahead.

The inferno just north of Los Angeles rapidly burned through almost 15,000 acres (60 square kilometers) over the weekend, forcing the evacuation of more than a thousand campers from a recreational park and the closure of a popular boating lake.

Some 1,150 firefighters were working to contain the so-called "Post Fire," dousing the flames from seven air tankers and constructing perimeter lines, but it remained just eight percent contained by Monday morning.

The blaze is "exhibiting extreme fire behavior," warned the National Interagency Fire Center, with low visibility and winds of up to 50 miles (80 kilometers) per hour impeding firefighters' efforts.

It was one of around a dozen mostly smaller fires to ignite over a weekend in California that saw high temperatures, low humidity and gusty winds.

The blazes come at the start of a potentially critical time for the notoriously fire-prone region.

In the western United States, recent wet winters have prompted the rapid growth of vegetation, which experts warn could prove dangerous as it dries out in the weeks and months ahead.

Grasses and trees in parts of California are already "sufficiently dry to support elevated fire weather concerns, and recent fire activity suggests that fuels are drying quickly and supportive of fire spread," said the National Weather Service.

"As the result of two consecutive wet winters, there is a lot of additional growth, particularly of grass, but also, to a lesser extent, of heavier brush too," said Daniel Swain, a climate scientist with the University of California, Los Angeles.

"Those grasses are starting to dry out," although this early in the summer there is still some moisture, he added.

Wildfires are a natural -- and necessary -- part of the region's life cycle.

But climate change, caused by humanity's burning of fossil fuels -- which releases greenhouse gasses into the atmosphere -- is making extreme weather conditions more intense and frequent.

A potentially historic heat wave is set to hit vast swaths of the central and eastern United States this week, where temperatures are expected to be unseasonably high for June.

Scorching temperatures have already broken early summer records in the western United States.

Earlier this month Las Vegas recorded a 111 degree Fahrenheit (44 degrees Celsius) day earlier in the year than ever before.

Some 42,000 acres have already burned in California this year -- around 50 percent higher than the five-year average by this point in the year.

Echoing a national trend, wildfires in 2024 have been fewer in number, but larger in size, than in recent years.