Search under way: Mother arrives in Halls Gap to join search for son

He has not been heard from since 7.15pm after going on a solo hike late Wednesday.

"Jack video called his family to let them know he was at the top of the Pinnacle Point walking track at 7.15pm," Victoria police said in a statement.

His vehicle has been located nearby at Schools Road.

"Police and family hold concerns for the safety and welfare of Jack as he is autistic and is not equipped for the weather conditions," police said in the statement.

"Local police units are searching the area with assistance from police air wing and SES volunteers."

Jack is described as being about 175cm tall, of slim build with brown hair.

He was last seen wearing blue shorts, a t-shirt that is black, grey and white in colour, black runners and a brown akubra style hat.

Anyone with information on his whereabouts is urged to contact Ararat police station on 5355 1500.

Earlier: The concerned mother of a 20-year-old missing after going on a bush walk in Halls Gap has called for people to keep an eye out for her son.

On Wednesday, January 3 about 1pm Jack Baulch decided to head to Halls Gap from Ballarat to explore one of the many bush walks.

His mother Katrina Baulch said she spoke to her son, who has autism, a number of times throughout the day.

Mrs Baulch said her son, who enjoys bushwalking, sent her a message while on the Pinnacle walk.

"At 7.15pm he sent me a message to say he had arrived at the top," Mrs Baulch said.

She has not heard from her son since.

His phone now goes straight to message bank.

Mrs Baulch said it was extremely out of character for her son to not contact her or not return home.

She alerted police at 2am and a search began on Thursday morning.

Mrs Baulch and family members have arrived in Halls Gap to join the search.

Her son's car is parked in the main street where he would have left it before setting off on the walk.

Mrs Baulch said she was extremely grateful to police and the SES.

A post she shared on Facebook has also been shared dozens of times.

Mrs Baulch has shared a photo of her son wearing the clothes he set out for his walk on.

She said he was almost six feet tall and had a medium build.

"Jack walked the Pinnacle at Halls Gap late yesterday and hasn't returned," Mrs Baulch said in the Facebook post.

"He's been uncontactable since 7.30 pm. This is what he was wearing.

"Search and rescue under way but if anyone is in the area please keep a look out for him and call his name."

Anyone with information is urged to contact Halls Gap police on 5356 4411 or Crime Stoppers on 1800 333 000.