Parts of the islands saw a metre of rain in 60 hours, the country’s Metservice said. It added that a further 200m to 300m of rain was expected to cause “dangerous river conditions and significant flooding” over the coming day.
On Monday, a state of emergency was declared when 382 people became trapped in the region.
It is a popular tourist region, with visitors who flock to the area for its scenic beauty including the snow-capped Southern Alps and glacier-carved valleys.
Some of the tourists were able to stay overnight at a lodge on higher ground.
Others were forced to stay on tourist boats.
The region’s emergency management controller Angus McKay said: “They have plenty of food and are safe and warm.”
On Tuesday, some 30 tourists were rescued by helicopter from Howden Hut, near Fiordland’s Lake Howden.
The hut was hit by a landslide in the early hours of the mooning, leaving two occupants with minor injuries.
The helicopters lifted off at around 7:40am local time, after having to wait for a break in the weather.
He told Radio New Zealand: “The river was up on the road and it must have been 10 feet higher than it would normally be.
“It was horrifying and I knew from that point ‘no, you can’t go forward anymore because if you get stuck here, that’s it, it’s just going to lift you into the river’.”
He eventually managed to reach higher ground and spent several hours stranded before being rescued by helicopter.
MetService forecaster Lewis Ferris said one metre of rain had fallen in 60 hours in Milford Sound, and 600mm of that fell in the 24 hours to about 7am yesterday.
Mr Ferris said: “Those are numbers some of our most experienced forecasters haven’t seen before.
“So 1000mm in an entire event has been seen before, but to get that in two-and-a-half days has been quite a lot.”