A wet start to the week is forecast for parts of the North Island

MetService has issued heavy rain watches are for Northland, Auckland and the Coromandel Peninsula.

Starting any time now, heavy rain's expected for Auckland north of Orewa and Northland south of the Bay of Islands.

MetService says the Northland region north of the Bay of Islands remains under a heavy rain watch until 3 in the morning.

Heavy rain is expected to move slowly south towards Auckland, and thunderstorms are possible in Northland tomorrow morning.

The heavy rain watch period is expected to end in the early hours of Tuesday morning.