MetService say a heavy rain watch is now in force for the Bay of Plenty.

"A narrow band of heavy rain is possible about the eastern parts of the Bay of Plenty region during Monday, and a Heavy Rain Watch is now in force," says a MetService spokesperson.

The area that is likely to be most affected is in the Bay of Plenty from about Kawerau eastwards.

The heavy rain watch is valid for 15 hours from 2am to 5pm on Monday.

"A narrow band of heavy rain producing localised downpours is possible on Monday, mainly during the morning.

"The exact location of this narrow band of heavy rain is uncertain at this stage, but if it occurs, it could cause localised surface flooding, especially if it affects an urban area like Whakatane."

An update for severe weather will be issued by the MetService by 9pm on Sunday February 20.