A seven degree start in Tauranga this morning marks the arrival of a southwesterly flow covering most of New Zealand.

Embedded in the weather system is a weak front forecast to move onto the far south on Tuesday night.

Ahead of this, the MetService has issued a severe weather outlook for the week ahead.

"A shallow low over the Tasman Sea should spread rain onto northern New Zealand at night. There is minimal risk of severe weather affecting New Zealand," says an update from the weather organisation.

"On Wednesday, May 29, a shallow low should move eastwards across the north of the North Island, followed by strengthening southwesterlies.

"here is low confidence of a period of severe southwest gales about eastern parts of Dunedin and Clutha, and about exposed parts of Auckland, Great Barrier Island and Coromandel Peninsula from Pauanui northwards."

On Thursday, a strong west to southwest flow will be covering the country, with an embedded weak front forecast to briefly affect southern New Zealand.

There is moderate confidence of a period of severe west to southwest gales about Stewart Island and coastal parts of Dunedin, Clutha and Southland, as drawn on the chart.

On Friday, May 31 a strong west to southwest flow over the country will turn northwest over southern New Zealand ahead of a front approaching from the Tasman Sea.

There is low confidence westerly gales will become severe for a time about Stewart Island and coastal parts of Southland and Clutha, and about exposed parts of the Tararua District and Hawke's Bay south of Cape Kidnapp