The Bay of Plenty is on a heavy rain watch today.

It may not look like it outside, but the MetService is forecasting heavy rain for parts of the North Island for Tuesday through to Wednesday.

"A low is expected to deepen over the Tasman Sea today and approach the North Island late Tuesday into Wednesday," says the MetService.

"Fronts associated with this low are expected to move east to southeastward over the North Island during late Tuesday and Wednesday, bringing heavy rain to parts of the North Island and Watches are now in force.

"This is a developing event and people are advised to stay up to date with the latest forecast, in case part of these Watches are upgraded to an Orange Warning or further areas are added."

HEAVY RAIN WATCH

Area: Bay of Plenty west of Whakatane

Valid: 15 hours from 3pm Tuesday to 6am Wednesday

Forecast: Period of heavy rain. Rainfall accumulations could approach warning amounts.

Area: Taranaki north of Eltham, including the Mountain

Valid: 12 hours from 10pm Tuesday to 10am Wednesday

Forecast: Period of heavy rain. Rainfall accumulations may approach warning amounts.