Another vigorous subtropical storm is making a beeline for the North Island, bringing strong winds, heavy rain and thunderstorms.

It threatens to cause more slips and floods for regions across the top of the country still reeling after last week’s deluge.

Niwa said the bad weather will be spawned from moisture in the tropics and is expected to affect Northland tomorrow evening before becoming more widespread across the weekend.

A heavy rain watch for Northland will come into force at 3pm tomorrow and go through to 3am Friday. A strong wind watch is in place for the area at the same time.

MetService has also issued a heavy rain watch and strong wind watch for Auckland and Great Barrier - the rain warning comes into effect at 9pm while the wind warning kicks in an hour earlier.

Similar heavy rain watches and strong wind watches have also been issued for Coromandel, Bay of Plenty and Rotorua.

Niwa said the storm could be damaging.

The forecaster reported that the odds for wind gusts exceeding 70km/h is high for much of the North Island on Friday and Saturday. Some areas could also get wind gusts of more than 100km/h.

Between 50mm and 100mm of rain is possible for parts of the island by midnight Friday.

MetService said the bands of rain will be fast-moving, and it expects large waves along exposed coastlines.

In the South Island, Westland and Fiordland are under orange heavy rain warnings.

Up to 150mm is likely about the ranges of the South Island.

A heavy snow watch will come into force for Central Otago and Queenstown Lakes from 9pm tonight and a road snowfall warning is in place for the Crown Range Rd from 10pm.