A heavy rain watch has been issued for the Bay of Plenty.

The MetService is forecasting heavy rain and strong winds for central parts of New Zealand, as well as snow about the South Island High Country.

"A front is expected to move up the South Island from the southwest today followed by cold southerlies, while a trough affects central New Zealand," says the weather organisation.

"A low is expected to develop northwest of Taranaki overnight Wednesday, deepen and become slow-moving during Thursday, then move slowly northwards on Friday.

"These features are expected to bring periods of heavy rain to central parts of New Zealand, and snow to the South Island High Country. South to southeast gales are also expected for central parts of New Zealand during Thursday and Friday."

A Heavy Rain Watch is in force for Marlborough, Wellington, Horowhenua, Kapiti Coast, the Tararua Range, and northern Taranaki, Bay of Plenty and the Gisborne ranges.

A Heavy Snow Watch is in force for the Canterbury High Country south of the Rangitata River.

A Strong Wind Watch is also in force for coastal Marlborough, and in Westland and Buller north of Hokitika.

"People are advised to stay up to date with the latest forecasts in case any changes are made or further areas are added."

HEAVY RAIN WATCH

Area: Bay Of Plenty, Rotorua, and the ranges of Gisborne

Valid: 27 hours from 9pm Thursday to 12am Saturday.

Forecast: Periods of heavy rain. Rainfall amounts may approach warning criteria.

Area: Taranaki north of the mountain

Valid: 19 hours from 2am to 9pm Thursday

Forecast: Periods of heavy rain. Rainfall amounts may approach warning criteria.

Area: Kapiti Coast and Horowhenua

Valid: 19 hours from 11pm Wednesday to 6pm Thursday.

Forecast: Periods of heavy rain. Rainfall amounts may approach warning criteria.

Area: The Marlborough Sounds including Rai Valley

Valid: 12 hours from 3pm Wednesday to 3am Thursday.

Forecast: Periods of heavy rain. Rainfall amounts may approach warning criteria.

Area: Wellington including the Tararua Range

Valid: 25 hours from 11pm Wednesday to 12am Friday.

Forecast: Periods of heavy rain. Rainfall amounts may approach warning criteria.

Area: Coastal Marlborough south of Seddon

Valid: 24 hours from 5pm Thursday to 5pm Friday.

Forecast: Periods of heavy rain. Rainfall amounts may approach warning criteria.

HEAVY SNOW WATCH

Area: Canterbury High Country south of the Rangitata River

Valid: 8 hours from 8pm Wednesday to 4am Thursday.

Forecast: Snow is expected to fall 500 metres during this period.

Significant accumulations are possible above 800 metres and may approach warning amounts.

STRONG WIND WATCH

Area: Coastal Marlborough from Ward northwards.

Valid: 17 hours from 1pm Thursday to 6am Friday.

Forecast: South to southeasterly winds may approach severe gale in exposed places at times.

Area: The south of Buller and Westland north Hokitika

Valid: 22 hours from 2pm Thursday to 12pm Friday.

Forecast: Southeast winds may approach severe gale in exposed places at times.