Northland, Auckland, the Coromandel Peninsula, Bay of Plenty and Gisborne are in for wet weather on Thursday.
MetService had issued heavy rain watches for all five regions, though by 8am the watches for Auckland and Northland were lifted.
Coromandel Peninsula, Bay of Plenty and Tai Rāwhiti could have localised downpours and thunderstoms through to 6pm.
"We could see heavier falls at times today, thunderstorms, and even downpours," MetService meteorologist Mmathapelo Makgabutlane said.
"The warning amounts we're expecting could be a bit disruptive for some places, so plan ahead."
Makgabutlane said the weather system would also bring in warm, moist air.
"We're expecting temperatures around the mid-20s during the daytime today, which is not unusual for this time of year.
"However, as night time comes, that humid air and all of the clouds around will be keeping things quite warm."
Temperatures would reach the high 20s in some areas on Friday, Makgabutlane said.
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