A motorist called emergency services after being trapped by rising floodwaters on Waiteitei Rd, north of Wellsford. When fire crews arrived they found three abandoned vehicles on the submerged road.
Deep flooding on State Highway 16 at West Coast Rd between Kaukapakapa and Wellsford had made the road impassable.
The New Zealand Transport Agency said flooding has closed six roads around the Rodney District and others are passable but flooded.
A slip has closed Matakana Valley Rd and two slips were partially blocking lanes on Pakiri Rd.
Foodwaters were also affecting State Highway 1 at Dome Valley and Purewa, south of Whangarei.
WeatherWatch.co.nz warned plenty more rain is to come and flooding may get worse.
Heavy rain was covering a narrow area from Great Barrier Island, north of Albany and south of Whangarei.
Motorists were advised to drive with extreme care and with lights on and watch for slips and flooding.
Farmers were advised to stay away from flood waters and not to cross flooded highways or tracks.
Ahuroa School principal Michelle Nell said many pupils came from areas currently inundated by floodwaters and it was important parents could get their children home before roads were cut off.
She said three other schools in the area had closed for the day including Tauhoa, Wellsford and Tomarata Primary.
Depending on the extent of the flooding the school could also face a second day closed.
MetService warned another 90mm was expected to fall across the rain-soaked region by 9pm tonight.
Further south, overnight sub-zero temperatures were felt by many in the lower North Island and South Island overnight - the Mt Cook region was forecast to get as low as -8C.
Police warned motorists of icy conditions on roads around Wellington this morning and urged people to take care particularly in valleys and shaded areas.
However, Flynn said the cold snap of the past few days was beginning to lift, and temperatures are expected to creep back into the double digits throughout the day.
Flynn said it was too early to tell whether the freezing temperatures would lift in time for spring, but said August was "colder than average for the time of year".
Last night the Napier-Taupo Rd was opened to motorists four days after heavy snow hit Hawke's Bay.
NZTA highway manager Wayne Oldfield said crews had been hard at work since last Friday and were faced by one of the heaviest snowfalls in the region in recent years.
Six snow ploughs and "an army" of loaders had been used around the clock to tackle the snow.
Yesterday afternoon, the NZTA was warning motorists to drive with caution on highways around the central North Island because of "winter driving conditions" on the Desert Rd, between Tutira to Wairoa, Otoko to Matawai and the Rimutaka Hill Rd.
"In general, road users are advised to continue to take extra care and drive to the conditions. As weather and road conditions can change rapidly we advise people to check the latest weather and road updates before they get on the road," NZTA said.
Further south, no snow warnings were in place for alpine passes, but motorists in Canterbury were being warned to take care as frost was expected.
"Extreme caution is advised for motorists using the roads on Banks Peninsula. Due to the current wet road conditions, icy conditions are quite possible."
Today's weather
Whangarei: Rain at times, chance of thunder. Southeasterlies. High 15 Low 9
Auckland: Rain at times. Southeast, strong in exposed places. H 12 L 8
Hamilton: Occasional rain from late morning. Gusty southeasterlies. H 13 L 5
Tauranga: High cloud, showers. Southeasterlies. H 14 L 8
Napier: Cloudy, few showers. Easterlies. H 13 L 7
Wellington: Becoming fine in the morning, frost in valleys. Light winds. H 12 L 5
