The MetService has issued five orange warnings for the South Island up until Tuesday.
Heavy rain and strong winds have been forecast for Canterbury until tomorrow morning.
Severe northwesterlies are expected in exposed places in Canterbury, gusting up to 150km/h in the High Country.
Heavy rain warnings are also in place for Westland, south of Otira, and the headwaters in Canterbury - particularly south of Arthur’s Pass.
Environment Canterbury is urging people in flood-prone areas to monitor the situation and move stock to higher ground.
Orange warnings indicate there is a likelihood of significant disruption, along with potential risk to animals, people and property.
The severe weather warnings follow similar storm conditions last week, which caused surface flooding and heavy snow.
An active front from the Tasman Sea approached the South Island yesterday and was expected to move northeast over the island today and tomorrow.
The front is being flagged as a "significant severe weather event", and brings an expectation more areas could be added and some places might be upgraded to red warnings.
A red warning indicates immediate action is required to protect from the significant impact of wild weather.
The orange warnings indicate that an expected 36 hours of heavy rain, with possible thunderstorms, at the headwaters of many popular Otago lakes and rivers will likely cause streams and rivers to rise rapidly.
There is also a risk of surface flooding, slips and hazardous driving conditions.
The rain is expected to ease about 1am tomorrow.
Similar conditions in Fiordland are expected to last until 11pm today, with up to 280mm of rain accumulating north of Doubtful Sound.
In Central Otago, there was some surface flooding on roads around the district this morning and more rain was forecast throughout the day.
Waka Kotahi/ NZ Transport Agency's Tresca Forrester told RNZ this morning the rain was expected to be particularly severe in some mountain passes and along the West Coast.
"We're just advising extreme caution if you are heading out into the high country across the mountain pass. The rain is going to be really heavy and intense, particularly through places like Arthur's Pass, Burkes Pass and down into the MacKenzie Country, Twizel, Tekapo, and across the West Coast as well."
Strong wind warnings
Strong northwesterly winds have also been flagged, with gusts of up to 130km/h expected in exposed locations in Otago until 11pm today, and up to 120km/h in Fiordland, Southland and Stewart Island until 7pm.
Drivers have been warned that travelling on motorcycles and in high-sided vehicles could be dangerous. Damage to trees, powerlines and unsecured structures is also a risk.
The gales are expected to be worst in Otago.
Waka Kotahi's Tresca Forrester said people shouldn't underestimate the wind factor.
"The wind is forecast to be very strong in places and particularly if you are heading away with caravans, high-sided vehicles like a campervan, just really take extra care because it can sneak up on you on the road."
Severe northwesterlies are expected in exposed places in Canterbury, gusting up to 150km/h in the High Country.
Warnings of north west gales gusting up to around 120km/h are in place for Marlborough, Otago, Southland, Fiordland and Stewart Island.
"The advice is, things can change really quickly."
A strong wind warning was also in place across the Queenstown Lakes district, a spokesman for the council advised this morning.
"Any high-sided vehicles or vehicles towing something behind them should be mindful of this, especially if you're heading over the Crown Range.
"While the roads might not be icy, there's still going to be plenty of surface water and grit to contend with, so please take it slow. As the rain continues, we're likely to see a few slips on some roads too."
Milford Road closed
Snow was falling last night in Milford Road (State Highway 94) but had turned to sleet and a warning for further snow lifted.
However, the area of SH94 around the Homer Tunnel was closed yesterday due to an avalanche risk, and expected to be closed for much of today, the Waka Kotahi NZ Transport Agency website said.
oscar.francis@odt.co.nz
- additional reporting RNZ
