Mt Cook Airport in the Mackenzie Country was a close second with a mercury reading of -8.1C.
The central North Island's ski district was also bitterly cold.
Desert Road dropped to -7.7C and small Waiouru - home of the National Army Museum - fell to -7.3C.
It came after Kiwis took that moment longer to get out of bed and brave the freezing cold this morning.
That included tiny Twizel near Aoraki-Mt Cook in the South Island's Mackenzie Country where the mercury had climbed to -3C at 7am after plunging as low as -6C overnight, forecaster MetService said.
Christchurch and Timaru residents in Canterbury, meanwhile, earlier woke to morning temperatures of -2C today, while Queenstown was an even chillier -3C.
Christchurch could expect to reach a high of 10C today on what would be a fine day after morning cloud cleared.
Elsewhere in the South Island, Invercargill was sitting on 0C at 7am, while Dunedin was a positively balmy 3C.
Ohakune near the central North Island ski fields, meanwhile, dipped to as low as -4C overnight with lake resort town Taupō dropping to 0C.
Aucklanders weren't immune from the cold as those in the nation's biggest city faced a 7am temperature of 5C with an expected high of 14C ahead on an otherwise fine Saturday.
Chilly Hamilton, meanwhile, dipped to -1C overnight with a fine top of 13C ahead, while Rotorua was sitting on 2C at 7am.
Wellingtonians started their day with the mercury at 5C at 7am as a fine high of 11C was forecast for the afternoon.
Even the winterless north was shivering with Whāngarei residents waking to 5C temperatures with a showery top of 15C ahead.
Tauranga's 7am temperature of 6C was expected to climb to 15C later today.
The chilly morning continued on from earlier in the week with Auckland reaching its coldest temperature in three years on June 30 as -3C was recorded at Whenuapai
Forecaster MetService said the first few days of July would likely be a repeat, being spent under an area of high pressure with settled and mainly fine weather.
"Cold mornings and crisp days are on the menu for most of us," it said.
"Come the week beginning Monday 5th, this high will break down and edge away east, allowing the first in a succession of Tasman lows to move in from the west."
It tipped that July would be a wetter month but also warmer than average for most regions of the country.
"This doesn't rule out the odd cold outbreak ... it just makes it the exception rather than the rule," it said.
