A very cold south to southwesterly airflow lies over the country today, thunderstorms with hail look likely north of northern Waikato. Snow showers will affect lower and coastal eastern parts of the South Island, snow lowering to 300m about the lower North Island late afternoon also.

Northland, Auckland, northern Waikato
Showers, heavy and thundery at times with hail then easing later in the evening. Winds strong from the southwest easing at night. Showers clear overnight.
Highs: 12-13

Central North Island, Bay Of Plenty & southern Waikato
Showers and snow flurries to 500m clearing by midday then sunny spells increase, winds change cold southwest early on. About southern parts of the Central North Island including the desert road showers continue through the afternoon and evening with snow lowering to 400m.
Highs: 7-13

Eastern North Island
Showers, mainly about Wairarapa with snow to 400m, the odd shower further north with a few sunny spells at times. Cold southwesterlies. Showers move into Gisborne in the evening.
Highs: 10-12

Western North Island
Showers, heavy and possibly thundery at first then easing during the afternoon and clearing overnight. Dry spells at times during the afternoon and evening. Winds brisk and cold from the southwest.
Highs: 8-10

Wellington
Early showers and snow to 500m eases then expect cloudy periods and the odd shower at times with flurries lowering to 300m in the afternoon. Winds strong to gale force from the south. Late afternoon showers intensify with a risk of hail, snow continues to 300m.
Highs: 8-9

Nelson
Sunny with southwest breezes, perhaps a little brisk in the afternoon.
Highs: 10-11

Marlborough
Mostly sunny with some cloud, cool gusty south to southwest winds.
Highs: 9-10

Canterbury
Sunny spells and some cloud with gusty cold southwesterlies. Wintry showers on Banks Peninsula with snow flurries to low levels. Mid afternoon showers push into areas east of about Rakaia north through to Amberley and a few areas of snow may make it to sea level by evening, snow is likely on the Port Hills. The foothills of Canterbury while mainly dry may still get the odd flurry or two in the afternoon and evening. Wintry showers with snow flurries to low levels and possibly sea level push into the coastal fringe of north Canterbury in the evening affecting the inland Kaikoura ranges area also. Southwesterlies rising to gale force about the coast especially Banks Peninsula late afternoon and evening. Shower activity easing overnight.
Highs: 6-7

West Coast
Mainly sunny, any early showers about and north of Greymouth clearing. Cold southwesterly winds die out in the evening with frosts developing overnight.
Highs: 10-12

Southland & Otago
Snow, a few heavy falls inland at first then easing during the afternoon to clear by evening, bitterly cold southwest winds. Becoming very cold inland at night with temperatures potentially dipping down to -9 degrees celcius.
Highs: 2-6

WeatherWatch.co.nz