The Coromandel Peninsula and parts of Bay of Plenty are in for a damp start to the second week of school holidays, with a heavy rain warning issued.

MetService said all of the Coromandel Peninsula, and much of the Bay of Plenty, including Rotorua, could expect up to 110mm or 120mm of rain in the 12 hours from 8am Monday into Monday night or early Tuesday morning.

They advised drivers to drive cautiously, for people to avoid low-lying areas, and to prepare for the rain by clearing drains and gutters so rainwater would not build up.

Streams and rivers could rise rapidly, and the rain could build up as surface flooding and cause slips.

Forecasters have also issued a heavy rain watch for Northland, Auckland north of Whangaparāoa and the Tasman District around Motueka.

Those areas could be in for a period of heavy rain approaching the intensity of the orange warning criteria.

Thunderstorms were also likely for Northland and Auckland thunderstorms were likely, and gale strength winds in Northland.

The rain would arrive with a frontal system coming from the north Tasman Sea.

People are advised to keep up to date with the latest forecasts via MetService.