A severe weather watch is in force for the Bay of Plenty.

The MetService is forecasting heavy rain for northern parts of the North Island.

"A low-pressure system over northern New Zealand and its associated rain-band, are expected to move slowly southeastwards over northern parts of the North Island during Thursday night and Friday morning.

"People are advised to keep up to date with forecasts in case any changes are made."

HEAVY RAIN WATCH

Area: Northland south of Kaikohe
Valid: 3 hours from 7pm to 10pm Thursday
Forecast: Rain, with localised heavy falls. Rainfall amounts may approach warning criteria in some places.

Area: Auckland (excluding Great Barrier Island)
Valid: 13 hours from 7pm Thursday to 8am Friday
Forecast: Rain, with localised heavy falls. Rainfall amounts may approach warning criteria in some places.

Area: Coromandel Peninsula, and Bay of Plenty north of Papamoa
Valid: 8 hours from 7pm Thursday to 3am Friday
Forecast: Rain, with localised heavy falls. Rainfall amounts may approach warning criteria in some places.

Area: Waikato near the west coast
Valid: 6 hours from 1am to 7am Friday
Forecast: A period of heavy rain is possible, and rainfall amounts may approach warning criteria.

Area: Mount Taranaki
Valid: 11 hours from 7pm Thursday to 6am Friday
Forecast: Periods of heavy rain, and amounts may approach warning criteria.