Over a metre of rain fell in parts of Fiordland in just over a 60-hour period - over three times the monthly average - from Sunday to Tuesday, causing major flooding and landslides, trapping hundreds of tourists and trampers.
Great Walks the Routeburn Track and Milford Track suffered major damage in the storm, with dozens of visitors needing to be evacuated by helicopter.
On the Routeburn, a landslide crashed through Howden Hut, with a hiker - one of 31 seeking shelter inside - telling the Herald it was lucky nobody was killed.
The Department of Conservation said following the "significant damage", the Routeburn Track would not reopen for the rest of the season - which ends April 30 - and remain closed for the "foreseeable future".
The track would require "considerable repair work to be operational", DoC said in an update.
Kiwi hiker Grace Houpapa told the New Zealand Herald of how they sought shelter in Howden Hut, just an hour and a half from the end of the walk, after a massive landslide, about 30m wide, had cut off the track ahead and there was no way of getting through.
But during the night as they awaited helicopter rescue another landslide crashed into the hut, toppling a large tree that crushed a section of the building, nearly killing a man who had moved from his bed only a minute earlier.
The Milford Track will be closed to the public for at least three weeks while DoC sought to undertake critical repair work.
"We are aware of significant damage to the Milford end of the track with some of our early assessments," the update said.
Both tracks are incredibly popular.
The Routeburn, which is generally completed over two or three nights, is full over most of the holiday and peak summer periods, but is largely booked out for the season. Huts there cost $65 a night for New Zealand citizens and $130 for international visitors.
People who have booked the Milford for the period up to February 29 will be given a full refund for bookings made through the Great Walks system.
People who have booked the Routeburn Track for the remainder of the summer season would also be given a full refund.
These refunds would be processed "as soon as possible".
Doc said it understood the closures would be disappointing, but its priority was safety for staff and visitors.
"We understand that this is disappointing for people who have been booked to walk at this time.
"Unfortunately, assessments to both the Milford and Routeburn tracks have shown extensive damage that will take time to repair.
"Our priority is ensuring people's safety. No access to either track will be possible while we undertake this repair work."
The Kepler Great Walk remained open and operational.