A severe thunderstorm watch is in place for Rotorua.
MetService said thunderstorms embedded in a rain band were expected to affect the Bay of Plenty, Rotorua, Coromandel Peninsula and Great Barrier Island overnight Saturday and
early Sunday morning.
Some of those thunderstorms could become severe.
"These severe thunderstorms if they occur have the potential to bring localised downpours of 25 to 40mm/h," MetService said in a statement.
"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. Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain."