Showers will be more frequent about Taranaki, Waitomo and Taumarunui.
In Gisborne and Hawke's Bay there will also be occasional showers about the ranges.
"It will be mainly fine elsewhere apart from the chance of an afternoon shower," MetService said in its forecast to midnight.
Across Whanganui, Wellington and the Wairarapa there will also be occasional showers, starting this afternoon.
Some showers, possibly heavy downpours, are also forecast.
In Buller, Nelson and Marlborough, showers, some heavy, are expected this morning.
Thunderstorms with hail are also possible about western Nelson and northern Buller.
While Westland will remain mostly fine, Canterbury will be plagued by clouds and scattered rain this afternoon.
But that rain should clear across the Plains this evening.
Scattered rain will also hit Otago, Southland and Fiordland but should clear by the afternoon, when there will be long fine breaks.