A swathe of the upper North Island is being warned of potential thunderstorms and torrential rain on Sunday night.
MetService has issued a severe thunderstorm watch for Auckland, including Great Barrier Island, Northland, the Coromandel and the Bay of Plenty, with an active trough expected to pass quickly southeast on Sunday night and Monday morning.
"This evening, a moderate risk of thunderstorms develops in the north of Northland, and spreads southwards, reaching Auckland and the Coromandel Peninsula at night," MetService said.
The forecaster said there is potential the thunderstorms could bring small hail and a low risk of coastal tornadoes.
People in these areas are also being warned of localised downpours with an intensity of 25-40mm per hour.
"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 said.
"Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain."
The forecaster has also issued a heavy rain watch for Bay of Plenty east of Whakatāne and Gisborne north of Ruatoria, saying a period of heavy rain with thunderstorms and isolated downpours are possible.
"Amounts may approach warning criteria. Moderate chance of upgrading to a warning," MetService warned.
Severe Thunderstorm Watch timing and locations
Northland - 6hrs from 6pm - midnight Sun, 16 Jun
Auckland, Great Barrier Island - 5hrs from 9pm Sun, 16 Jun - 2am Mon, 17 Jun. Areas about and near the Hauraki Gulf are most likely to experience the downpours, but they may also occur elsewhere in Auckland.
Coromandel Peninsula 4hrs from 11pm Sun, 16 Jun - 3am Mon, 17 Jun
Bay of Plenty, Rotorua - 5hrs from 1am - 6am Mon, 17 Jun
Heavy Rain Watch timing and locations
Bay of Plenty east of Whakatāne, and Gisborne north of Ruatoria - 8hrs from 3am - 11am Mon, 17 Jun
