A 60-year-old hiker has been missing in the wilderness near Lake Tahoe, California, since Memorial Day, sparking a desperate search that is now closing in on a week.

Jason Coughran, 60, went missing on May 25 as he hiked into the Desolation Wilderness area from Fallen Leaf Lake, the El Dorado County Sheriff's Office said.

The Desolation Wilderness is a 63,930-acre area of wilderness land just west of Lake Tahoe that includes glacially-formed valleys and lakes.

Coughran was last heard from around 4pm that day, authorities noted.

A missing person's poster for Coughran added that it was believed he was seen hiking near Angora Peak roughly five hours earlier.

He was described as a 6-foot-2, 150 pound male adult with brown hair, hazel eyes, an athletic build and believed to be wearing khaki shorts.

Ground teams, K9 units and helicopters from El Dorado County's Echo One and Washoe County in Nevada have been used in the search for Coughran so far, according to the Mountain Messenger.

The California Governor's Office of Emergency Services joined the search mission on Friday.

The weather in Lake Tahoe was clear and mild when Coughran went missing on Monday, but turned much colder and windier by the following afternoon.

Light snow and fog were also seen that day, according to the San Francisco Chronicle.

South Lake Tahoe Airport recorded gusts that topped 40 miles per hour.

On Saturday night, some fog was expected around 1am but it was otherwise clear with calm wind and a low of 33 F.

The El Dorado County Sheriff's Office noted that the weather could be 'unpredictable in the high elevations,' which would include Angora Peak.

Hikers were urged to plan accordingly when venturing into the wilderness.

A Reddit user, who identified herself as Rachel and said she was Coughran's friend, said the best way to help him was by 'staying off the trails and letting the professionals collect the data they need to collect to determine where he may have gone.'

'If we go out there by ourselves, we risk stepping on what may have been his footprints, or impacting other data that could lead to his ultimate rescue or recovery,' she added.

Rachel said Coughran had her old Apple Watch, but that the 'find my' feature showed its last signal at their apartment complex.

She also posted photos of Coughran's day hike in an attempt to obtain more information about his possible whereabouts.

As of Saturday night, 192 personnel were working on the search and rescue effort, according to the El Dorado County Sheriff's Office.

Law enforcement said an Air National Guard CH-47 Chinook helicopter had dropped off 80 search-and-rescue volunteers into Desolation Wilderness.

Meanwhile, another 60 volunteers entered by vehicle, with 50 of them set to stay overnight to continue looking for Coughran.

The California Governor's Office of Emergency Services, which says on its website that it is responsible for 'protecting Californians' lives and property,' described the search rescue as a 'large-scale' operation.

Drones and helicopters, which could be seen in footage released by the agency, were being used in the search.

The Daily Mail has reached out to the El Dorado County Sheriff's Office and the California Governor's Office of Emergency Services for comment.