Wellington would also be cooler with highs in the low double digits this week and overnight the temperature would remain largely unchanged because of the wind and cloud.
Auckland, Hamilton, Tauranga and other northern New Zealand centres would also be cooler with highs reaching about 12C to 14C, compared to late teens last week, Mr Duncan said.
Poor weather last week closed two roads in the South Island.
A large rock slip in the Kawarau Gorge yesterday has closed State Highway 6 between Cromwell and Queenstown. It was not known when roading contractors would be able to have it cleared.
Heavy snow yesterday has also closed SH 94 between between Te Anau and Milford Sound.
The New Zealand Transport Agency did not know when the road would reopen.
STRONG WINDS
Strong wind gusts have torn down a shed in Himatangi Beach, west of Palmerston North.
The fire service is still at the property where the shed had blown onto the road, a fire service spokeswoman said.
Some corrugated iron from the shed had landed on powerlines but no other properties had been damaged by the wind, she said.