Weather: Heavy rain on the way for South Island, flooding possible

A significant rain event is expected to hit the South Island this week. Photo / Supplied

A significant rain event is expected to hit the South Island this week.

Metservice is predicting that up to 550mm of rain could fall in the ranges.

A MetService spokesman said an active front, preceded by a moist and strong northerly flow, was forecast to move northeast over the South Island from Wednesday to Friday, bringing significant heavy rain to the West Coast.

Though high pressure keeps the weather settled over NZ for another couple days this will change on Wednesday when a band of subtropical moves over the South Island.

Keep updated with the latest forecast as Severe Weather Watches & Warnings are likely to be issues with this event pic.twitter.com/0qQJ96TBKz

— MetService (@MetService) January 30, 2022

The heaviest rain was expected in Westland.

''Orange Heavy Rain Warnings are now in force for Westland and Buller. There is a possibility that the warning for Westland may be upgraded to a Red Warning closer to the time.

''In addition, Heavy Rain Watches are now in force for Fiordland, the headwaters of Otago and Canterbury lakes and rivers, and also the northwest part of Tasman.''

The weather event was expected to affect the headwaters of Otago lakes and rivers from 5am on Wednesday until 5am on Thursday, and Fiordland from 1pm on Wednesday until 10am on Thursday.

The spokesman said the heavy rain could cause streams and rivers to rise rapidly.

''Localised flooding and slips are likely, and driving conditions may be hazardous during the event.''

He urged residents to keep up to date with the latest MetService warnings and watches.

"It's possible we will see a rare red warning later this week due to the incoming rain."