Extra emergency service workers are being deployed in the hunt for six canyoners missing since Tuesday in the NSW Blue Mountains.
The canyoners - two boys aged 13 and 15, two women aged 25 and 27 and two men aged 25 and 27 - are likely to still be in good health, Blue Mountains Local Area Command Crime Manager Detective Inspector Michael Bostock says.
"We know they had enough food for one day so they might be hungry by now but there is plenty of water in that area and we had rain overnight," he told AAP.
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The search around Wollangambe Canyon near Mt Wilson in the Blue Mountains National Park was hampered on Thursday morning by low cloud which grounded search and rescue helicopters.
The weather is expected to clear later in the day, allowing the helicopters to join the hunt.
Also in the Blue Mountains, some resources have been diverted to help look for a missing 85-year-old man with Alzheimers disease in Hazelbrook, near Katoomba.
But extra police, ambulance, Rural Fire Service (RFS) and National Parks and Wildlife Service staff are being drafted in to bolster the canyon operation.
They join around 40 police, RFS workers and paramedics who began the search on Wednesday after relatives of the canyoners reported them overdue on Tuesday afternoon. Police dogs are also scouring the area.
Fairfax newspapers reported that some relatives of the canyoners had arrived at the Mount Wilson Rural Fire Service base where the search is being co-ordinated.
Earlier, Detective Inspector Bostock said the group members were not carrying emergency beacons.
But he said they were relatively well prepared and some of the party were experienced.
The cooler weather on Thursday would also aid rescue teams on the ground, he added.
"Look, we're concerned, obviously they are well equipped with clothing and one of the party has got some experience of being in that canyon at least twice before, once in the last 12 months," Mr Bostock told Fairfax Radio Network.
"If they stay put, hopefully rescue will find them.
"They had a plan, whether they stuck with that or diverted somewhere else we can only speculate. Maybe they've missed a turn or taken a wrong track ... depends how good their map was.
Last year British backpacker Jamie Neale survived 12 days lost in the Blue Mountains.
