A low will remain slow-moving over the Tasman Sea on Monday, directing a showery northwest flow over the North Island, says MetService.

Meanwhile, a trough is lying over central New Zealand, with a ridge building to the south of the country.

"A strong southeast flow is forecast to develop over the South Island between the trough and ridge, with gales likely in exposed places," says a MetService spokesperson.

"Snow is also forecast for the Canterbury High Country and southeastern parts of Marlborough, which may affect some high roads."

MetService says there is low confidence of rainfall amounts reaching warning criteria about eastern Bay of Plenty and the far north of Gisborne/Tairawhiti, and also about northwest Tasman, northern and southeastern Marlborough, and the northern Canterbury High Country, as depicted on the chart.

Tuesday June 18
A broad low remains slow-moving over the Tasman Sea, while a trough over central New Zealand moves northwards and a ridge continues to build to the south of the country.

This directs a strong southeast flow over New Zealand, with gales likely in exposed places. Snow is also forecast for the Canterbury High Country and southeastern parts of Marlborough, which may affect some high roads.

There is low confidence of warnable amounts of rain for the southeast of Marlborough and the northern Canterbury High Country, as indicated on the chart.

Wednesday June 19
A broad low remains slow-moving over the Tasman Sea, with an associated weak trough extending over northern New Zealand.

A high to the southeast of the South Island extends a ridge over southern and central New Zealand, and the strong east to southeast flow over the country should begin to ease. At this stage the risk of severe weather is considered minimal.

Thursday June 20
A broad low remains slow-moving over the Tasman Sea, with an associated weak trough extending over northern New Zealand to just west of the South Island.

A high to the southeast of the South Island moves slowly eastwards, with winds continuing to ease and turning east to northeast. At this stage the risk of severe weather is considered minimal.