Flights to Wellington, Christchurch, Dunedin and Queenstown, and international flights, have so far not been affected.
Aucklanders can expect a high of 16C and an overnight low of 8C tonight. A few showers - possibly heavy - are forecast just before dawn and will ease by this evening.
Showers are forecast for Northland, Coromandel Peninsula and Waikato.
Periods of rain are expected in Waitomo to Wellington including the central high country and Bay of Plenty region. Fine spells are expected later this afternoon, but the Bay of Plenty will be in for some heavy rain and possible thunderstorms.
It will be mainly fine in Gisborne, Hawke's Bay, Wairarapa and Marlborough, save for a few spots of rain this afternoon.
Cold front comes in today
A cold front is expected to move of the southern part of the country today and then over the rest of New Zealand tomorrow. MetService says: "Most places in New Zealand will receive a period of rain with the front, followed by a change to strong, cold and showery southwesterly winds.
"Daytime temperatures are forecast to drop by 4 to 7 degrees following the cold front and places exposed to the strong southwesterly winds will feel even colder when you factor in the wind chill.''
Severe weather warnings have also been issued for parts of the South Island.
Heavy rain is expected in Westland and there is a heavy snow warning in the Canterbury High Country and foothills - from the Rākaia River southwards - and central Otago north of Omakau.
The cold front over the South Island is set to bring snow down to 300 to 400m in some parts.
"A period of significant snowfall is expected above 600m about the Canterbury High Country and foothills south of the Rākaia River and also northern parts of central Otago.
"A heavy snow warning is now in force for these areas," MetService said.
A heavy rain watch remains in place for Westland from Hokitika southwards.
Road authorities in the South Island are encouraging motorists in the area to stay alert and up-to-date with road conditions and any advisories.
In Haast Pass (SH6), snow is expected to affect the road for a time this afternoon. Between 1 and 3cm of snow is expected near the summit, with lesser amounts down to 300 to 400m.
In Lindis Pass (SH8), snow is expected to affect the road from this afternoon. Between 5 to 10cm of snow above 600m is expected between 3pm to 10pm with lesser amounts down to 300 to 400m.
Snow is also expected to affect the Crown Range Rd from this afternoon. Anything from 5 to 10cm of snow above 600m is expected between 2pm and 10pm.
Snow showers are also expected to affect the Milford Road (SH94). Snow of up to 5cm is forecast to settle on the road above 600m with lesser amounts down to 400m.
