A severe weather watch for heavy rain is currently in force for the Coromandel Peninsula.

The MetService is forecasting heavy rain and snow for southern New Zealand, and heavy rain and northeast gales for northern parts of the country.

"A front associated with a low pressure system over the Tasman Sea is forecast to move slowly northwards over southern New Zealand this evening and early Thursday morning," says the latest update from the weather organistion.

"The front should then move offshore to the west. Northerly winds are expected to turn colder southeasterly behind the front, bringing the snow level down to around 300 metres in parts of Southland, Otago and Canterbury for a time.

"Meanwhile, another front associated with the low is expected to move southwards over northern New Zealand during the latter part of Thursday and Friday, bringing a period of heavy rain and strong or gale force east to northeast winds.

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

Heavy Rain Watch

Area: Northland
Valid: 9 hours from 2pm Thu 20 Jul to 11pm Thu 20 Jul
Forecast: A period of heavy rain, and amounts may approach warning criteria.

Area: Auckland and Great Barrier Island
Valid: 9 hours from 9pm Thu 20 Jul to 6am Fri 21 Jul
Forecast: A period of heavy rain, and amounts may approach warning criteria.

Area: Coromandel Peninsula
Valid: 18 hours from 11pm Thu 20 Jul to 5pm Fri 21 Jul
Forecast: A period of heavy rain, and amounts may approach warning criteria.

Area: Tairawhiti/Gisborne
Valid: 24 hours from 6am Fri 21 Jul to 6am Sat 22 Jul
Forecast: A period of heavy rain, and amounts may approach warning criteria.

Area: Westland south of the glaciers
Valid: 12 hours from 7pm Wed 19 Jul to 7am Thu 20 Jul
Forecast: A period of heavy rain, and amounts may approach warning criteria.

Area: Fiordland
Valid: 18 hours from 12pm Wed 19 Jul to 6am Thu 20 Jul
Forecast: A period of heavy rain, and amounts may approach warning criteria.

Heavy Snow Watch
Area: Canterbury High Country south of Lake Tekapo
Valid: 6 hours from 2am Thu 20 Jul to 8am Thu 20 Jul
Forecast: A period of heavy snow, and amounts may approach warning criteria above 600 metres.

Strong Wind Watch
Area: Northland
Valid: 9 hours from 2pm Thu 20 Jul to 11pm Thu 20 Jul
Forecast: Northeast winds may approach severe gale in exposed places.