Charlie Clift, 56, was last seen buying outdoor clothing on Tuesday 30 January in Fort William town centre.
Highland and Islands Police said they were increasingly concerned about Mr Clift's welfare.
Lochaber Insp Andrew Bilton said they were asking hikers to keep an eye out for him.
He said: "Given the lack of contact from Mr Clift and the decline in weather conditions, his family, friends and officers are understandably increasingly concerned for Mr Clift's welfare."
Police are searching for a man from south Wales who went missing while hiking in Scotland.