Police are warning drivers to take care on Rimutaka Hill Rd this afternoon.
Snow has started to fall at the summit.
Metservice said showers and snow above 600m were expected in Kapiti, Wellington, Gisborne to Wairarapa, Southern Taranaki and Wanganui.
Showers would be more frequent and heavier in Wellington and Wairarapa this evening.
A deep low to the east and high pressure to the west had been pushing a cold southerly flow over New Zealand since Tuesday.
MetService said the cold weather was expected to start clearing on Saturday, but it wouldn't feel warmer across the country until Monday.
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