Heavy rain is being forecast for the Bay of Plenty today, with a heavy rain watch in force from the MetService.

"Moist northwesterlies with a number of embedded fronts are forecast to affect the country through to Friday, bringing periods of heavy rain to northern and western areas of the South Island.

"A trough embedded in the northwest flow is expected to cross the North Island during Tuesday, bringing a period of heavy rain to the Bay of Plenty, and also strong or gale north to northwest winds to Taranaki, Wellington and Wairarapa, which may approach severe gale strength in exposed places at times," says the weather organisation.

"Please note, that for western areas of the South Island this is a significant rain event and that total accumulations are likely to exceed 400mm in some places over the next four day's period.

"People are advised to stay up to date with the latest forecasts in case new Warning or Watch areas are added."

Roads will be slippery as a result of the rain and people are advised to drive to the conditions.

Heavy Rain Watch

Area: Bay of Plenty east of Rotorua
Valid: 9 hours from 9am to 6pm Tuesday
Forecast: Periods of heavy rain, and rainfall accumulations may approach warning criteria.