Most of the South Island is under orange strong wind or heavy rain warnings for Monday before an even more significant front arrives later in the week.
Otago is under a strong wind warning from 5am to 2pm Monday where severe gale northwesterlies could gust up to 120km/h.
Another period of severe gales is possible for Tuesday.
Damage to trees, powerlines, and unsecured structures is possible, the forecaster warned.
Southland, including Fiordland and Stewart Island, is under a similar wind warning, running from 2am to noon Monday.
Heavy rain is expected for Fiordland north of Doubtful Sound, the Westland ranges, the headwaters of Otago and Canterbury's lakes and rivers and the Grey, Buller and Tasman districts.
That heavy rain is due throughout most of Monday, beginning in the South from about 2am Monday.
At least 100mm of rain is expected in most areas, rising to 250mm about the main divide.
The more severe of the two weather systems this week is due to hit the South by Thursday, MetService warned.
No warnings or watches have yet been issued "but the potential is there for this to be a highly impactful event", the forecaster said.
Snow for alpine passes, Milford Rd closed
Southland's Milford Rd (SH94) was closed from East Gate (Hollyford) to Donne River (Westgate) at 5pm today due to overnight snow forecasts.
It was expected to reopen on Tuesday mid-morning, with a possible further closure overnight on Tuesday with reopening on Wednesday when snowfall and clearing allows, the Milford Road Alliance advised.
An all-day closure on Thursday is also possible with another large weather system increasing the avalanche hazard.
- Allied Media
