A cold front leaves the upper South Island this morning then hits the North Island, many regions will see rain or showers with snow in the ranges, more details below.

Northland, Auckland, Waikato & Bay Of Plenty The odd shower in the west, showers beef up around midday spreading to all as southwesterlies freshen, winds become strong in the west. There is a chance of hail with heavy showers and thunder then easing back during the afternoon, showers clear Bay Of Plenty by evening.
Highs: 13 – 15

Western North Island (including Central North Island)
Occasional showers from late morning as westerlies change southwest, snow flurries to 800m. Rain moves in from the south overnight with strong southerlies. Snow overnight to 700 or perhaps 600m, possibly heavy.
Highs: 5 – 14

Eastern North Island
Sunny spells, a few showers from afternoon as southwesterlies freshen, coastal gales from evening. Rain develops later in the evening south of Napier with snow lowering to 700 or perhaps 600m.
Highs: 12 – 16

Wellington
Sunny spells, a few showers mainly in the north. Breezy northwesterlies change southerly around midday. Late afternoon or evening southerlies rise to gale with severe gales developing through Cook Strait. Widespread evening showers then rain overnight with snow to 600m.
Highs: 11 – 12

Marlborough & Nelson
Sunny spells, morning showers for Nelson clear. A few showers move into Marlborough evening as southwesterlies freshen. Snow flurries above 700m, rain overnight for southern Marlborough with snow to 600m.
Highs: 13 – 14

Canterbury
Morning sunny spells, cloud thickens from afternoon with a few showers moving in north of about the Rakaia River as southwesterlies strengthen. Rain overnight for the Kaikoura area. Severe coastal gales possible. Snow flurries to 400m from evening.
Highs: 10 – 12

West Coast
Rain clears from the south with sun increasing, remaining showers clear southern Fiordland and Buller in the evening. Snow to 600m in the north, 300m for Fiordland. Gusty southwesterlies die away in the evening.
Highs: 10 – 12

Southland & Otago
Rain eases to showers in the morning for Southland, afternoon for Otago, showers clear evening. Gusty southwesterlies (gale about the coast) die out later in the day. Snow to 400 or perhaps 300m.
Highs: 8 – 10