Up to 1000 people are stranded in Franz Josef after heavy rainfall caused a huge slip in the area, in the latest event of the weekend's wild weather.
Westland Mayor Bruce Smith said he and government officials will check residents and assess the situation on a helicopter ride on Monday.
They are in the process of organising food packages and water for affected residents, he said.
The road to the glacier is not expected to reopen until "at least Friday 13th December".
The only road between Hokitika and Wanaka/Haast will be closed "for weeks and weeks, if not months and months", he said.
He said the situation was terrible for the tourism industry in the area, which was already facing problems and low earnings.
Power was also out from Fox Glacier to Paringa, and was likely to remain so for a couple of days.
It follows a weekend of drastic weather across the country, yet a reprieve from the flooding, thunderstorms, lightning strikes and flooding is expected.
Niwa tweeted there had been 300,000 lightning strikes on Sunday.
MetService forecaster Paul Ngamanu said that the current front bringing thunderstorms will slowly move off the North Island in the next few days, as a ridge brings fine weather to much of the country.
It will be a chance for many areas to mop up, after horrendous weather lashed the country at the weekend.
A heavy rain warning and severe thunderstorm watch was set for Wellington, where pelting rain caused surface flooding.
After a brief break, another spell of heavy rain hit the capital on Sunday, and areas around Porirua and Hutt Valley, where flooding had earlier subsided, began to overflow once again.
State Highway 2 northbound near Belmont was down to one lane on Sunday afternoon, and landslips, debris and damage to the road surface forced State Highway 58 to close between Pauatahanui and the Haywards interchange.
NZ Transport Agency regional systems manger Mark Owen told the Herald the latest rain was proving a challenge for the clean-up.
"The crews are on stand-by ready to finish the repairs but they won't know until that rain goes through, and any subsequent damage that may be caused, what it'll take to repair the network."
He said they would be working hard through the night to try and ensure the road was open up this morning.
This came the day after a cluster of thunderstorms hit the city on Saturday night, with Fire and Emergency Services receiving over 25 flooding-related calls since 6am on Sunday.
And the thunderstorms continued on Sunday evening, Ngamanu said, before eventually settling for a quiet start to the week, with fine weather expected on Monday and Tuesday.
A local state of emergency was declared further south in Timaru, after a one-in-20-year flooding of the Rangitata River has blocked State Highway 1.
Local residents between McLelland, Orion Rangitata Mouth Roads and Rangitata River were told to evacuate the area immediately on Saturday and the main highway through the West Coast was blocked off on Sunday evening.
The Timaru District Council confirmed there would be no road connection north to Christchurch on Sunday evening.
The council said it was a dynamic situation and the first stage was getting rid of the water, before working to try to create a driveable surface.
State Highway One bridge at Rangitata and the route 72 bridge at Arundel was closed due to significant flooding and Timaru's mayor Nigel Bowen called on people to be patient, and said everyone was working to get things open as soon as possible.
Drone footage over route 72 at Arundel showed the full extent of the damage caused by the flooded Rangitata River: cutting the South Island in half.
The road seal was ripped up and chunks were in part of the road in the drone footage, as flood water gushed high and fast over the road, pooling on either side.
A man who forced to sleep in his car in Geraldine, after the awful weather severed access to the airport, was told by his rental car company Apex that they had 200 cars stranded either side of the divide.
Civil Defence said efforts were being made to get the bridge at Arundel open on a limited basis on Sunday afternoon.
The upper Rangitata bridge crossing was being prioritised, as it would see water levels drop to a manageable level hours before the downstream bridge at State Highway 1.
Masses of stranded visitors left Timaru for Geraldine, only to find there was no access to eftpos or cash machines.
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Running Duck Cafe owner Alistair Bolland said it wasn't only causing issues for hospitality sector, with all the camping grounds and motels are full at the weekend.
Sandbags and plastic sheets covered the front of most businesses in Wanaka on Saturday, as the lake levels remained about 25cm below the flood alert threshold.
Queenstown Lakes District Council shut down the street's sewerage system amid fears of Lake Wanaka flooding.
Ngamanu said the remaining showers in the area are expected to clear this evening, with a fine weather expected for Monday and Tuesday.