The MetService said gales were likely to be worst in Hawkes Bay, Wairarapa, Manawatu and Marlborough, with gales of 50km/h, gusting to twice that speed, in Hawkes Bay and Wairarapa.
The wind would also pick up in Bay of Plenty and Auckland, but it was unlikely to be as strong.
Auckland could expect gales of 40km/h, with gusts up to 60km/h in exposed places.
MetService duty forecaster Leigh Matheson said Auckland would get some fairly strong westerlies.
"Basically what's happening is there's a fairly active low that's deepened off Tasmania and it's heading towards us now.
"There's quite a good band of rain coming on to the West Coast, but it's fairly weak as it comes on to the North Island," he said.
The low will also bring showers to Northland, Auckland, Wellington and the east, from Gisborne to Wairarapa, today.
Tomorrow, when the clocks move forward an hour, there will be isolated showers turning to rain in the evening, especially in the west.
In the South Island, the MetService has issued a heavy rain warning for Westland, Buller and Canterbury from today through tomorrow.
The heaviest rain was expected to fall in the Southern Alps, which would get up to 160mm in 24 hours.
Late September through to early November tend to be New Zealand's windiest months.