Carolyn is visiting from the United States. Her daughter Rachel is a student at Massey University.
Family members, the rental company and the motel have not heard from either of the women.
Massey University spokesman James Gardiner said Rachel was at the university on a one-semester exchange and had arrived from the US in February.
He said the university was cooperating with the investigation and was in contact with police as well as family members.
"We will offer Rachel's father transport to New Zealand, and are offering the family our support," Mr Gardiner said.
"We don't know what the situation is yet, but it is very worrying."
MetService meteorologist Arno Byason said there had been settled weather in the Tararua range in past few days.
"There's been no significant rainfalls or strong winds. It should remain fairly settled until late Sunday when there'll be strong winds which carry through to Monday."
MetService recorded temperatures dropping to 6C in Levin on Wednesday morning. MetService's weather station in Levin, west of the range, is its closest station to the track.
A six bunk hut is situated on the track, with heating, mattresses and a water supply.
Anyone with information on the whereabouts of Carolyn Lloyd, Rachel Lloyd or the vehicle should contact Palmerston North Police on 06 351 2535.