LOS ANGELES — Major wildfires in Southern California were kept at bay amid cooler, more humid weather, while blazes elsewhere in the West saw big growth and potential danger.

Improved weather in the aftermath of a severe heat wave allowed firefighters to make progress against two fires in the steep San Gabriel Mountains 20 miles northeast of Los Angeles.

A fleet of helicopters and air tankers and other resources are helping fight the fires totaling about 7½ square miles.

Despite fears that stronger winds could make the fire resurgent and the challenges of tough terrain, containment was expanded from 10 to 15 percent by Wednesday evening.

No homes have been lost, though flames have come close at times. More than 850 homes were ordered evacuated earlier this week, and 534 homes in the foothill city of Duarte were cleared for residents’ return Wednesday.

Near the Mexican border, two residences and 11 outbuildings burned in a wildfire about 40 miles southeast of San Diego. About 200 structures were threatened by the blaze, which grew to just over 10 square miles and was 20 percent contained.

Elsewhere in the West, a forest fire near the Colorado-Wyoming line exploded in size and forced campers to evacuate.

A shift in the wind turned a blaze burning slowly in a heavily wooded area with no permanent residents into a fast-moving threat, growing from 1 square mile to about 5. Trees killed by a beetle infestation were fueling the flames 140 miles north of Denver and 2 miles from Wyoming.

More firefighters were expected, but getting more help was difficult because of the other Western blazes. “Resources are kind of hard to come by right now,” Routt National Forest spokesman Aaron Voos said

In southwest Utah, a fire forced evacuations of at least 185 homes in the town of Pine Valley. The U.S. Forest Service said Wednesday that the blaze has torched more than a square mile and additional evacuations could come.

In eastern Arizona, firefighters expected to keep a wildfire spanning about 67 square miles from moving any closer to a rural town. More than 15,000 people in nearby mountain communities have been told to prepare to evacuate.