Two elderly bushwalkers are still missing in the Blue Mountains west of Sydney after they were last seen five days ago.
Alfred Zawadzki, 69, and Klaus Umland, 81, left Dunphy's campground in the Megalong Valley on Wednesday, telling a friend they would be back on Friday.
The search began after the alarm was raised on Sunday when Mr Zawadzki failed to keep an appointment.
Mr Umland's car was later found in the car park of Dunphy's campground.
"We will search until we find them," NSW Police Acting Inspector Lauren Martin said on Monday.
A storm hit the area on Sunday, followed by 30C temperatures on Monday.
One of the men is believed to have managed to make a phone call to his family on Sunday morning, but the call was hampered by patchy reception, according to Nine.
However, the searchers, including those from State Emergency Service, think they have some idea of where the bushwalkers might have been hiking, NSW Police told AAP on Monday.
They have also been told the two men may have decided to extend the duration of their hike.
But police still want to speak to anyone who may have seen the pair in the area since Friday.
Mr Zawadzki is about 180cm tall with a medium build and grey hair, while Mr Umland is about 170cm with grey hair. Both are off Caucasian appearance.
The men are experienced bushwalkers and police believe the trail they intended to take was within their capabilities.
A command post has been established at Dunphy's campground with local police, the rescue squad and the SES.