More than 70mm of heavy rain has fallen in Westland today with the forecast predicting the South Island region to reach over 90mm.
The downpour is causing headaches as rivers continue to rise, reaching the same level as during the 2016 floods which caused damage worth $30 million.
Emergency services have been forced to close a number of roads and schools throughout the West Coast with some areas getting over half a metre of rain since Sunday.
Civil Defence West Coast is warning motorists to be careful on the roads as strong winds power up with the heavy rain to make dangerous driving conditions.
State Highways: Warnings and closures
Canterbury (Including Alpine / Mountain Passes): SH73 Springfield to Arthurs Pass – Strong Winds
West Coast: SH6 Hokitika to Ross - CLOSED – Flooding – Road is closed due to heavy rain, rising rivers and slips. Report will be updated by 8 am Wed 27 March.
SH6 Franz Josef to Haast – CLOSED – Slip - Due to slips and heavy rain the road will remain closed today and overnight with the next update expected at 8 am Wed 27 March.
SH6 Ross to Haast – Surface Water – Caution – Heavy rain has resulted in surface flooding in many areas
Otago: SH6 Haast to Makarora – CLOSED – Slip - Due to slips and heavy rain the road will remain closed today and overnight with the next update expected at 8 am Wed 27 March.
Southland: SH94 Te Anau to Milford Sound – Surface Water – Caution – Heavy rain warning. Road surface flooding and slips possible.
MetService is forecasting parts of Fiordland and the West Coast could receive 700mm of rain between Sunday and today - more than half the annual total for Auckland.
Westland District Mayor Bruce Smith said it was raining steadily throughout Tuesday with much more to come.
Localised flooding on South Turnbull Rd, in Okuru and also south of the Arawhata Bridge has led to self-evacuation of dwellings immediately south of the bridge.
He had just been down to the Waiho River, which was "bank to bank".
"It is well over 8 metres at the moment, which is of great concern.
"We are looking like it is going to continue raining like this. It may all blow over but the rivers really can't take much more before they burst their banks."
The rivers were similar to the heights of the April 2016 flood which caused "$30 million worth of damage".
"On the south of the Waiho we have significant dairy farms, the airport and a lot of tourism activities, so if the banks burst we go into evacuation mode, and we really don't want to have to do that."
He said there was about another half a metre the river could handle before they could have issues.
"We had 390mm of rain last night, and another 300mm is forecast in the next 15 hours. We have just got to hope it all goes down the river."
A strong and moist northwest flow was behind the "exceptional" amount of rain, especially around Milford Sound and Westland, ahead of an active front over the Tasman Sea.
An NZ Transport Agency spokeswoman said two slips at Omoeroa had closed a section of State Highway 6 between Franz Josef and Haast. This would be closed until 8am tomorrow.
SH6 was also closed between Hokitika and Ross due to heavy rain, rising rivers and slips, and between Haast and Makarora due to a slip. The next updates were due at 8am tomorrow.
Caution was also advised for drivers from Haast to Ross, and on SH94 from Te Anau to Milford Sound due to surface water.
There was also significant surface flooding in some locations, with water covering the road at Lake Wahapo, south of Whataroa. This area was on a 30km/h speed restriction.
There was minor surface flooding at Haast.
South Westland Area School was closed for the day.
Westland District Council has activated its Emergency Operations Centre and held a briefing with emergency services and support agencies at 8am.
The heavy rain could cause streams and river to rise rapidly. Surface flooding and slips were also possible and driving conditions could be hazardous with further potential road closures.
MetService meteorologist Stephen Glassey said Milford Sound had already had more than 400mm of rain since Sunday. The heaviest falls were overnight, with 124mm in five hours from midnight, with rainfall rates of 30mm an hour over a few hours.
There would be even larger accumulations in the ranges but there were no rain gauges in the hardest hit spots, Glassey said.
Farther north, Franz Josef had recorded about 160mm since Sunday, but the heaviest falls were expected today as the front edged up the country.
The rain would ease about Fiordland but intensify in Westland through the day before reaching Buller and the lower southwest North Island tomorrow.
There were still heavy rain warnings in place for many places including Westland south of Otira, the headwaters of the Canterbury lakes and rivers south of Arthurs Pass, headwaters of Otago lakes and rivers, and Fiordland.
Once the front reached the North Island there could be some heavy falls around Mt Taranaki and the Tararua Ranges, but it would have greatly weakened leaving just some isolated showers on the flats for the end of the week, Glassey said.
Today was looking fine for most other parts of the country, with just some scattered showers across the North Island.
Auckland would be mainly fine with just a chance of a shower and a high of 25C.
The country's east coast was looking the place to be once again courtesy of the warm foehn winds blowing down from the alps. Napier was in for a high of 29C while Christchurch would top the South Island once again on 25C.
Wellington could see some gale northerlies, but "nothing out of the ordinary", Glassey said.
The weakened front should then stall over the North Island on Thursday and weaken away on Friday, while a ridge of high pressure built over the country from the south.
Mainly fine, but chance shower. Northeasterlies. 25C high, 17C overnight.
Mainly fine, but chance shower. Northeasterlies. 25C high, 18C overnight.
Fine, apart from some cloud morning and night. Northerlies. 26C high, 14C overnight.
Cloudy periods, chance shower. Northerlies. 24C high, 18C overnight.
Whanganui Fine. Northwesterlies becoming gusty in the afternoon. 26C high, 17C overnight.
Wellington Cloudy with a few showers. Strong northerlies. 21C high, 18C overnight.
Nelson Cloudy, chance shower from afternoon. Northerlies strengthening in the afternoon. 23C high, 18C overnight.
Christchurch High cloud thickening during the day, then rain from evening. Northerlies, gale gusting 90 km/h about Banks Peninsula, easing at night. 25C high, 16C overnight.
Dunedin Occasional rain developing morning, clearing evening. Northerlies, strong for a time, easing in the afternoon. 25C high, 13C overnight.