Tauranga recorded 4.1C and Whakatāne 1.5C early doors.
MetService meteorologist Lewis Ferris said a cold air mass that moved in from the south Monday night into Tuesday had already put a chill into the air, but it was last night’s clear skies and light winds that allowed the temperature to drop extra low.
“-0.5C in Rotorua is pretty cold for an October morning, but just last year our station there set its October record low, dropping to -3.5C on October 7,” Ferris said.
Despite the bone-chilling temperatures, the next four days look promising with up to a 10C lift in average temperatures, according to Niwa.
The institute says a warm air mass from Australia will make it feel more like summer for some areas on Thursday and Friday.
Lewis said Bay of Plenty was also in for a run of fine and warm days to end the working week, but rain was forecast to arrive on Saturday.
With an area of high pressure sitting over the country, some eastern areas of the South Island would be heating up today, with Ashburton likely to be New Zealand’s hottest spot at 25C.