Search for Blue Mountains bushwalker

A large search is underway to find an experienced bushwalker missing for two days in the Blue Mountains west of Sydney.

David Bush, 75, was last seen at Evans Lookout in Blackheath about 9am on Saturday, and police are now seriously concerned for his welfare due to deteriorating weather in the area.

Mr Bush - who often goes on half or day-long hikes - has not made contact with relatives, NSW Police said in a statement on Monday.

He is described as being of Caucasian appearance, about 165-centimetres tall, with a thin build, short grey hair and brown eyes.

Mr Bush was wearing black nylon hiking pants, a black rain jacket and a black beanie. He was carrying a small bright blue backpack.

Police believe there were hikers in the area on Saturday and are appealing for anyone who may have been walking near Evans Lookout or the Grand Canyon track to contact them.