There will be a few morning showers in the Upper North Island today as humidity levels remain high. Meanwhile in the South Island the centre of a high pressure system dominates over the lower South Island but this will allow for afternoon thunderstorms to develop in the calm, humid, conditions (especially with a light humid NE flow along the eastern coastline).

NORTH ISLAND:
A few early drizzle patches and showers most likely in the upper half of the North Island then a mix of sun and clouds with afternoon downpours likely, some with thunder from Taranaki northwards. Elsewhere mostly dry with a mix of sun and cloud. Light easterlies in the north, light winds/sea breezes elsewhere.
Highs: 25 to 30 (but with humidity it may feel like the mid 30s for some).

SOUTH ISLAND
Some cloudy areas but plenty of sun and heat. Afternoon downpours forming inland around the ranges and foothills, some heavy with the chance of severe thunderstorms. Light winds and sea breezes. HOT! 
Highs: 25 to 33

– WeatherWatch.co.nz