Kiwis should pack an umbrella on Wednesday as rain and thunderstorms will lash the North Island.
NIWA said Wednesday will see the start of an extended period of showers, thunderstorms and downpours, particularly for the North Island.
This has seen MetService issue a severe thunderstorm watch for Northland down to the Wairarapa until 10pm on Wednesday.
The forecasting company said scattered thunderstorms are expected in western parts of Northland, which will bring heavy rain.
They also warned of a risk of severe thunderstorms producing localised downpours of 25-40 mm/h.
"Rainfall of this intensity can cause surface and/or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips," MetService warns.
"Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain."
MetService said the areas affected in the North Island are Auckland, Waikato, Waitomo, Taumarunui, Bay of Plenty, Taupō, Gisborne, Hawkes Bay, Taranaki, Taihape, Wanganui, Manawatu, Tararua, and Wairarapa.
WeatherWatch said typical La Niña weather is expected for New Zealand in the coming days, with thunderstorms and widespread downpours across the North Island and part of the South Island.
"The humid set up is due to a large low in the Tasman Sea which will linger until Sunday before finally falling apart," WeatherWatch said.
