Warning issued as wet, windy weather set to hit

The West Coast of the South Island is in for some wet and windy weather before the week's end, with some of it set to tip over the mountains and into Otago.

MetService has issued a heavy rain warning for Westland, north of Haast, that kicks in at 3am Thursday morning and covers the 24 hours through to early Friday morning.

The forecaster says up to 220mm of rain is expected to fall about the ranges, and up to 150mm about the coast.

A further period of heavy rain is expected later on Friday, and MetService expects to extend its warning closer to that time.

It warns streams and rivers could rise rapidly and surface flooding and slips are also possible.

MetService also has a heavy rain watch in place for Westland south of Haast, Fiordland, and the headwaters of Otago lakes and rivers, for much of Friday, when rain may approach warning criteria.

For Queenstown and Wānaka, rainfall amounts may approach warning criteria within 15 kilometres east of the main divide.

There is also a strong wind watch for Fiordland on Friday, and northerly winds may approach severe gale in exposed places.

A series of fronts bringing a humid northerly flow across the country are the cause of the unpopular school holiday weather.

"New Zealand's weather will be linked to the tropics this week...but it won't be all sunshine," NIWA's forecasters warn in a post to Facebook.

It says high humidity will be noticeable further north, while heavy rain will hit the top of the South Island on Thursday before travelling south, as moist air approaches the country from the north.