Recent slips on the hillside near the Durie Hill elevator have prompted the Whanganui District Council to close the Anzac Parade entrance next week.
A council spokesman said since initial repairs were carried out in March, there had been further movement near the entrance.
"Our contractors Downer have been monitoring the area, including a large root ball near the entrance," he said.
"Following recent substantial rainfall, there has been a significant increase in movement of the root ball, and there are concerns it may slide onto the footpath below."
Barriers had been installed at the base of the slope in the meantime, and to ensure the safety of those using the elevator, the entrance will be closed for five days from Monday, August 1 until Friday, August 5 to allow specialist contractors to remove the root ball and make certain the rest of the area remains stabilised.