Thunderstorms could be in store for Northland, Auckland, Great Barrier Island and Coromandel Peninsula on Sunday and into the early hours of Monday morning.
MetService says there's a moderate risk of thunderstorms embedded in rain extending south over the three areas.
"These thunderstorms are expected to bring heavy rain with intensities of 15 to 25 mm/h, and strong winds gusting 80 to 100 km/h.
"Additionally some of these thunderstorms could become SEVERE, producing localised downpours of 25 to 40 mm/h, as well as localised torrential rain with intensities greater than 40 mm/h. There is also a risk of a localised tornado occurring."
MetService warns of potential flash flooding and hazardous driving conditions.
Meanwhile heavy rain and strong winds are expected to hit parts of northern and central New Zealand on Monday, thanks to a slow-moving low-pressure system.
Waikato and Waitomo could see periods of heavy rain and thunderstorms until early Monday evening. This warning from MetService excludes the Coromandel Peninsula.
Gisborne north of Tologa Bay could also see some very heavy rain tomorrow and possibly on Tuesday.
Similar rain warnings have also been issued for Taumaranui, Taupo and Taranaki.
In the South Island, periods of heavy rain are expected early from Monday morning in Tasman west of Motueka and the Kaikoura Coast and Ranges.