California search crews Tuesday again braved sweltering temperatures to scour the Mojave Desert for a 69-year-old bikini-clad Arizona woman who vanished Friday while hiking with her husband -- and who reportedly had no supplies to sustain her in the unforgiving wasteland.

Barbara Thomas, of Bullhead City, Ariz., was last seen Friday hiking with her husband, Robert, in the desert about 20 miles north of Interstate 40, east of Kelbaker Road, according to the San Bernardino County Sheriff’s Department.

"Barbara and Robert got separated and she has not been seen since," the sheriff's office said.

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Thomas was last seen wearing a black bikini, red baseball cap and tan hiking boots with black socks.

"Barbara does not have any supplies or a cell phone," police said.

Search and rescue members, including sheriff's deputies, K9's, park rangers, and a helicopter have been deployed in the Mojave Desert as part of the team looking for Thomas.

"There have been no sightings of her at this time," according to the sheriff's office.

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Temperatures in the area climbed to more than 100 degrees over the weekend, with the high reaching 104 on Sunday. The forecast calls for temperatures to top the triple-digit mark during the week, too.

The National Weather Service warns heat is the top weather-related killer in the U.S.

Besides limited time outdoors and dressing appropriately, people can practice heat safety by staying hydrated, limiting strenuous activities and finding shade.

The search for Thomas comes amid the news Monday that a California mother and hiker who vanished during a camping trip in the White Mountains was found alive.

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Thomas is described as 5 feet 9 inches tall, weighing 130 pounds with blonde hair and green eyes.

Anyone with information regarding Barbara's whereabouts is urged to contact the Colorado River Station at 760-326-9200 or Sheriff's Dispatch at 760-956-5001.