Christchurch recorded -4C just after 7am, Queenstown -3C and Blenheim -1.2C.
A fine morning is forecast for the garden City. But frost and light winds are expected this evening.
Other places to hit chilly temperatures early today are Lake Pūkaki, Twizel, and Tūrangi, which recorded -6C shortly after 7am.
Despite the winter temperatures, people in Nelson, Westport, Blenheim, Christchurch and Franz Josef can all look forward to sunny skies today.
Meanwhile, heavy rain and "severe" gale warnings are forecast for the top half of the country.
Severe weather warnings have been issued for Northland, where periods of heavy rain are expected this afternoon and throughout the evening.
Up to 110mm of rain is forecast north and east of about Kaikohe and especially about the eastern hills. Heavier rain in western areas is on the cards from late this afternoon and accumulations may reach between 40mm to 60mm through early tomorrow morning.
Kerr said people on Great Barrier Island should also prepare for periods of heavy rain from tonight through to tomorrow morning.
Gisborne north of the city also has a heavy rain watch from about 11pm to 3pm tomorrow.
A strong wind watch has been issued for Auckland as well - just north of the Harbour Bridge, including Great Barrier Island and Coromandel Peninsula.
