At 7.20am MetService's main page map showed all main centres in the country on single-digit temperatures, topped by Stewart Island on 9C.
Dunedin was also high up the list on 7C, just below Gisborne's 8C.
The coldest place was Twizel, on -6.6C.
Several North Island locations were below zero, as much of the country woke to a foggy, frosty morning.
MetService had earlier warned of a particularly cold snap for the end of the week, with Friday expected to be the coldest day of the year for northern areas.
The forecaster predicted fog for many areas this morning but said it would clear for a mainly fine day for most of the country.
However, showers are on the way for the weekend, as a weak weather system moves across the country, bringing rain on Friday evening and Saturday.
