Schools are closed and roads are submerged as Northland is deluged by heavy rain.
State Highways 1 and 10 are swamped by floodwater and at least two Kaeo schools and a pre-school have closed for the day after flooding disrupted bus services.
Niwa says Kaitaia has had more rain so far today than the entire month of June.
The Far North has been hard hit by hours of non-stop rain with flooding hitting Kaeo, Taipa and Kaitaia.
Kaeo School and Whangaroa College have told students school buses are not running because of flooding.
Creative Minds Early Learning Centre had been cut off after Omauna Rd was inundated by rising floodwaters.
SH1 between Iwitaua and Mangamuka School Rd is down to one lane and flooding is starting to affect motorist just south of Kaitaia.
Niwa says Kaitaia has had 54mm of rain in the past 10 hours, which is more rain than the town has had in total this month.
MetService has issued a severe weather warning for Bay of Plenty and northern Gisborne.
Northland, Auckland and Coromandel Peninsula are under weather watches for heavy rain and gales today.
Bay of Plenty and northern Gisborne are next in the firing line, expecting 80mm to 110mm over an 15- to 18-hour period from this morning.
"Peak intensities 15 to 25mm an hour with thunderstorms possible," the MetService says. "Further heavy rain is possible late on Friday."
In the South Island motorists are being warned to expect up to 8cm snow on alpine passes today as the second chilly blast in a fortnight hits southern regions.
The Queenstown District Council said snow was falling on the top of Crown Range. It was closely monitoring conditions and warned there could be flooding and rockfalls on the region's roads.
Weather Watch says the north of the country, including Auckland, can expect morning rain to ease to showers after lunch.
"Northland may see a second wave of heavy showers/downpours in the afternoon with a chance of thunderstorms then easing in the evening," it says.
Rain is forecast for the east of the North Island, too, and strong southerlies are also expected to blow rain into Wellington.
Marlborough and Nelson will also experience southeasterly winds with rain moving in overnight and winds becoming strong.
Canterbury folk, light your fires. Weather Watch says "a cold southerly change develops in the morning bringing rain, easing to drizzle at times late afternoon. Snow to 800m in the morning, lowering to 400m in the afternoon about South Canterbury, 500m about Mid Canterbury and 600m about North Canterbury."
The West Coast is predicted to enjoy morning rain easing to showers in the afternoon, and early showers in Southland and Otago should also clear.
"Otago sees morning rain ease to the odd drizzle patch, snow flurries to 400m, perhaps even 300m at times."
The good news is summer is officially on its way with the daylight hours lengthening after the winter solstice yesterday.It was the shortest day of the year, the cue for gardeners to plant garlic and for hardy souls to take their traditional mid-winter swim. Workers from the Crown research institute Scion in Rotorua even braved the water in costume.
The water was just 12.3C at Rotorua's Lake Tikitapu but scientist Garth Weinberg, who organised the Polar Plunge, said there was a record turnout.
Seventy-eight staff took part in honour of Scion's Lucy Macdonald who died recently of cancer.
Solstice weather wasn't the best. Heavy fog halted flights in Christchurch and wind forced Auckland Transport to suspend ferry trips cross the Waitemata Harbour.
In the evening heavy rain began to pelt Westland, where it was expected to accumulate to warning levels of 100-120mm over 15 hours.
A band of rain was also hitting Northland yesterday evening and moving south, putting the entire country under a cloud today.
MetService meteorologist Kyle Lee said exposed areas were getting strong winds last night and by today most of the North Island would be wet.
From 9am today rain would be pelting the Bay of Plenty, Coromandel and Gisborne through until Friday, MetService said.
Those regions could be saturated by up to 100mm of rain falling over 18 hours, and thunderstorms are also in the mix.
People in these areas, especially trampers, are advised to look out for rapidly rising rivers and streams. Commuters should also take care as slips and surface flooding are possible, as well as severe gale watches in Northland and Auckland.
Residents were being warned to batten down the hatches overnight in preparation. A mini-tornado took tiles off a roof in Te Aroha, and the fire brigade put up a tarpaulin.
