The North Island clings to fine weather but parts of the South Island are firmly in the grip of a deluge.

MetService duty forecaster Arno Dyason said the North Island would be mainly dry today except for some isolated showers on the east.

"It's surprisingly a really good day but the wet weather is on the way," said Mr Dyason.

Auckland was in for another fine and warm 21C day while Wellington was expected to be fine with 18C.

Advertisement

But in the South Island the rain was starting to set in across western regions.

Mr Dyason said there would be heavy falls today and even a few spots of rain expected in the south and east.

The best weather was reserved for Christchurch, north to Marlborough, where it would be fine with high cloud.

Christchurch could expect 18C and Dunedin was in for a few spots of rain and 17C.