The search for a missing woman on New South Wales' far north coast has stepped up with aerial surveillance and police divers.
Amber Christie, 49, was reported missing by her family and friends after she failed to return to her Evans Head home from a Sunday afternoon walk.
Richmond Police Detective Chief Inspector Darren Cloake said it was out of character.
"We do have serious concerns for her health and welfare," he said.
"We know it has been cool overnight, and we do know that she was clothed in a cold weather jacket. But still, she would be in desperate need of food and water."
A multi-agency search is underway involving NSW Police, the State Emergency Service, surf rescue, and the Department of Defence which has a base near Evans Head.
Her last known sighting was walking past the Illawong Hotel in Evans Head just before 4:00pm on Sunday May 3.
Search coordinator Senior Constable Amanda Vidler said NSW Police fixed wing aircraft and drones were being used, as well as police divers who will search the Richmond River that runs through the centre of town.
"We are widening our search by the hour," Senior Constable Vidler said.
Detective Darren Cloake said Ms Christie had left the bare essentials at home to head out for exercise.
"[Her] phone was left at home with other belongings, so from all accounts it was a normal day or activity that she was undertaking," he said.
Detective Cloake said they were in constant contact with Ms Christie's immediate family and share their concerns for Ms Christie's safety.
"We will maintain that close liaison with family and immediate friends," he said.
Police said the Evans Head community was extremely supportive with 100 people turning up yesterday to lend a hand.
"The community has been very helpful every single day, we are still having people turning up at the command post offering assistance," Detective Cloake said.
Ms Christie is described as 162 centimetres tall, with an athletic build, and long auburn-brown hair often worn in a pony-tail.
Anyone with information about Ms Christie's whereabouts is urged to contact police on 1800 333 000.
