"There could be some heavy rain with this front, with some parts of the West Coast of the South Island looking at heavy rain in the late afternoon and into evening."
WeatherWatch said Nelson, the Marlborough Sounds and some western parts of the North Island could also expect some heavy rainfall overnight.
The warmest place this morning is Whangarei at 12C, while the coldest is Timaru at -6.5C, the MetService said.
The wettest place is Hokitika, with 0.2mm of rain, and Westport is the windiest this morning with gusts of 24km/h.
The MetService said Auckland should have cloudy periods and the odd shower today, with a strengthening northeasterly and a high of 15C.
Wellington would have a frosty start but an otherwise fine day with a high of 12C.
There was a similar outlook for Christchurch, according to MetService, with frost on the ground this morning, increasing high cloud throughout the day, and a high of 12C.