Southerlies spread onto the North Island on Thursday potentially bringing in a thundery change, cool for the South Island but brightening up for South Westland.

Rain or showers for most of the North Island on Thursday, thunderstorms possible about the Waikato and Bay Of Plenty then easing from mid afternoon.

Conditions gradually ease over the South Island although rain or showers may linger about the upper half through till evening, the odd heavy fall is even possible for the northwest Nelson area.

By Weather Analyst Aaron Wilkinson – WeatherWatch.co.nz