Two roads are closed in Wairarapa and Manawatu and the Rimutaka Hill Road is down to one lane late on Friday night as heavy rain batters the lower North Island.
MetService has issued a heavy rain warning for the area.
The Transport Agency says State Highway 53 between Featherston and Martinborough is closed after high flood levels in the Ruamahenga River.
Detours will add at least half an hour onto the journey in Wairarapa.
State Highway 56 in Manawatu is closed at Opiki, north of Shannon, because of high flood levels in the Manawatu River. Detours are also available there.
Desert Road reopens
The Desert Road in the central North Island reopened on Friday afternoon, after taking longer than expected to clear of snow, but drivers are being urged to take extra care.
State Highway 1 from Rangipo to Waiouru had been closed since Wednesday night due to snow of up to 1 metre in some places.