A fast-growing wildfire turned away from homes in San Diego County early Monday after prompting calls for evacuations, and hot, windy weather sapped the endurance of firefighters around the state.

The blaze in the Cleveland National Forest grew to 6,600 acres — more than 10 square miles — and prompted voluntary evacuations of hundreds of homes near Lake Morena, 60 miles east of San Diego, said Roxanne Provaznik of the California Department of Forestry.

The blaze moved rapidly south to southeast and away from homes, Provaznik said. It was only 5 percent contained by midday Monday and its cause was undetermined.

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Fire crews worked through the heat wave that has sent temperatures above 100 degrees. Firefighters in some parts of the state faced temperatures expected to hit 115 on Monday, officials said.

"It's making it really rough for our firefighters," Provaznik said.

Five firefighters around California suffered heat exhaustion during the weekend.

This fire season is on pace to be the worst year for wildfires this decade, the National Interagency Fire Center reported Monday.

As of Monday, wildfires had blackened more than 4.9 million acres, over 7,700 square miles, since the first of this year, the center reported. That surpassed the 4.8 million acres charred in 2004 and the 10-year average of 2.7 million acres. The season got a fast start with several weeks of spring grass fires that swept across Texas and Oklahoma.

Off the California coast, a blaze charred 700 acres — just over a square mile — of brush on Santa Catalina Island, the 76-square-mile recreation spot southwest of Los Angeles with several hotels and homes. It was 40 percent contained Monday and officials hoped to have it fully contained Tuesday.

In the San Bernardino Mountains, a complex of fires that had burned more than 38 square miles was about two-thirds contained, officials said. It has been stalled for nearly a week eight miles southwest of several communities.

In the mountains of central Idaho, high temperatures combined with wind to drive three forest fires. Managers worried that one of the fires could threaten federally protected chinook salmon.

Crews in central Arizona kept a 3,900-acre — or 6-square-mile — wildfire in the Tonto National Forest from reaching two power lines that carry electricity to Phoenix.

Unlike California, calmer wind and higher humidity helped crews battling a 3-square-mile blaze in western Nevada that had briefly threatened homes east of Carson City and the historic mining town of Virginia City during the weekend. It was 60 percent contained Monday and full containment was expected by the end of the day, said fire information officer Dave Olson.