Heavy rain and "severe" gale warnings are forecast for the top half of the country, while patchy weather conditions and some sun are expected for the rest.
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.
MetService meteorologist Rob Kerr said people on Great Barrier Island should also prepare for periods of heavy rain from tonight through to tomorrow morning.
A heavy rain watch is in place for Great Barrier, where rainfall amounts may reach "warning criteria".
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.
The watch is effective from about 6pm until 9am tomorrow and locals are told that south to southeast winds may turn into severe gales in exposed places.
Kerr said it did not look as if the strong winds could affect the Harbour Bridge itself.
Aucklanders are waking up to another chilly start to the working week.
Just before 7.30am, the temperature was officially recording as 7.4C - but the MetService website reported it feeling more like 4C and that three to four layers, plus windproof, of clothing was needed when venturing out.
A high of 12C is forecast in the City of Sails and an overnight low of 7C will mean for an extra blanket, at least, tonight.
Auckland is in for a morning shower or two and then scattered rain from this afternoon. Southeasterly winds are also expected in exposed parts of the city - with gales gusting up to 90km/h north of the Harbour Bridge by this evening.
Those in Hamilton are waking up to about 4.7C early this morning - although according to MetService, at 7.30am, that feels more like 1C outside.
High cloud is forecast in and around Waikato, with morning frosts and the possibility of the odd shower this evening.
In Wellington, the promise of a fine day - save for some high cloud - beckons today. However, there will be morning frosts in sheltered parts of the capital, as well as light winds.
A high of 11C is on the cards for Wellington and an overnight low of 4C.
Some frosty temperatures have been recorded around the country early today, with the coldest place being Hanmer Forest, in Canterbury, which clocked a teeth-chattering -7C early on.
"There's a lot of frost around, but I think we're going to be warming up a bit," Kerr said of this week.
Christchurch recorded -4C just after 7am - the same as Taumarunui, in the central North Island.
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.