Mr Duncan predicts that wind speeds will be high enough to uproot trees, break branches, lift roofing iron and make driving extremely difficult.
Although the weather is typical for Autumn, it will contrast heavily with recent, settled conditions, he said.
"We'll have heavy snow for parts of the Southern Alps, squalls with thunder on the West Coast, heavy rain for the West Coast and gales for eastern areas of both islands, especially the lower North Island - that's the extreme weather for the next 24 hours."
Wind and showers are predicted for many areas on Monday, easing on Tuesday with another high expected mid way through next week, to last until Saturday.