Thunderstorms and hail with the potential to cause damage are lashing parts of the North Island.
The thunderstorms were tonight moving towards Hamilton, after lashing central parts of the island.
The storms were earlier expected to affect the central North Island from Taranaki to the Hawke's Bay and further south to Manawatu.
MetService said the storms were likely to come with very heavy rain at rates of up 40mm an hour in some places, which could cause flash flooding.
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Large hail with the potential to damage vehicles is also expected.
The Fire Service said it had not yet had any reports or damage or flooding.
The storms are not expected to dissipate until later tonight.
The warning comes after freak thunderstorms lashed the upper North Island on Friday , cutting power and causing flash flooding in places.
Rain has been forecast for much of the country this week, after clear blue skies and hot temperatures saw New Zealanders finally enjoying the sun over the past two days.
A low coming across from New South Wales will bring rain and humidity, developing from today.
MetService's media and communications meteorologist Daniel Corbett said Otago and the West Coast of the South Island will see heavy rain from tomorrow.
Heavy rain is also expected for Nelson from tomorrow night until Wednesday morning.
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