Rim fire now the fourth-largest blaze in California history

The Rim fire burning in and around Yosemite National Park became the fourth-largest blaze in California history as it grew to 348 square miles Sunday, officials said.

More than 5,000 firefighters are battling the blaze, which began Aug. 17 and is 40% contained, according to the U.S. Forest Service. A September 1932 fire in Ventura County that burned 343 square miles previously held the fourth-place spot, Cal Fire said.

San Diego’s 427-square-mile Cedar fire, which destroyed more than 2,800 structures and killed 14 people in October 2003, remains the largest wildfire in state history.

Crews are making good progress on the Rim fire, particularly on its northwest side, though winds sparked new spot fires and the blaze is continuing to expand to the northeast, said U.S. Forest Service spokesman Trevor Augustino.

Winds have declined from earlier in the week, and a short rain shower Saturday night and higher humidity levels have helped mitigate some of the fire danger, he said.

“Any rain we get would be a tremendous asset,” he said, adding that the drought conditions and rugged, remote terrain have been challenging for firefighters.

Wind shifts Friday pushed smoke into the Yosemite Valley, which appeared hazy with decreased visibility Sunday afternoon in webcam images from around the park. Another shift in the wind is expected Monday or Tuesday, which should help clear the smoke out of the area, said park ranger Kari Cobb.

There has been a noticeable decline in visitors, she said, partly because of the fire’s smoke but also because of road closures.

Park officials are advising visitors to avoid strenuous activity and for those sensitive to smoke to avoid being outside.

The Rim fire has destroyed 111 structures, 11 of them residential, and is expected to be contained Sept. 20, said Cal Fire spokesman Daniel Berlant. No structures inside the national park have been lost, Cobb said. The cause remains under investigation.

Battling the blaze, the largest in California this year, has cost $60 million in state and federal funds, Augustino said.

Six other fires are burning in California, down from about a dozen last week, with more than 8,000 firefighting personnel deployed across the state, Berlant said. Recent weeks have seen an increase in fire activity, he said, because of dry conditions, gusty winds and dry lightning that sparked several hundred fires.

Fire officials are advising those camping over Labor Day weekend to be aware of fire restrictions when lighting campfires.

Some crews are being released as they reach the end of their two-week assignments, and reinforcements will be brought in as needed, Augustino said. Many are local contingents, he said, and are likely to be back after a few days of rest if they’re still needed.

Here is a list of California’s five largest wildfires:

1. The Cedar fire in San Diego County burned 427 square miles in October 2003, destroying more than 2,800 structures and killing 14 people. It began as a signal fire set by a West Covina man who was separated from his companion on a deer hunting trip, according to Times archives.

2. The Rush fire in Lassen County burned 424 square miles in California and 68 in Nevada in August 2012. It was sparked by lightning.

3. The Zaca fire in Santa Barbara County burned 375 square miles in July 2007. It was ignited by sparks from grinding equipment being used to repair a water pipe near Los Olivos, according to Times archives.

4. The 2-week-old Rim fire in Tuolumne County has scorched 348 square miles. It is 40% contained, and officials expect full containment by Sept. 20. The cause is under investigation.

5. The Matilija fire in Ventura County burned 343 square miles in September 1932. The cause is undetermined.

samantha.schaefer@latimes.com