A strong cold southwesterly airflow lies over New Zealand today.

Northland, Auckland, Waikato & Bay Of Plenty
Showers. From mid afternoon about the Waikato and late afternoon elsewhere showers increase in intensity as westerlies change fresh southwest, showers may be heavy with a risk of small hail for the Waikato and perhaps Bay Of Plenty.
Highs: 14-16

Western North Island (including Central North Island)
Showers about Taranaki spreading elsewhere by midday, showers may be heavy with hail / thunder from afternoon. Snow lowers to 500m about the Central Plateau. Gusty west to southwesterly winds, strong about coastal areas especially from midday.
Highs: 9-14

Eastern North Island
Mostly sunny then mid to late afternoon expect some cloud and the risk of a shower or spot of rain as northwesterlies tend gusty westerly.
Highs: 15-17

Wellington
Increasing cloud, a few afternoon showers pass through then becoming dry by evening. Strong northwesterlies tend westerly around midday, winds may gust to gale at times.
High: 13

Marlborough & Nelson
Sunny spells about Marlborough, northwesterlies tend gusty westerly in the morning. Nelson is dry at first the from mid or late morning expect showers and sunny spells with gusty westerlies.
Highs: 11-13

Canterbury
Sunny areas and some high cloud, west to northwesterly winds. Late afternoon or evening winds change gusty southwest reaching gale about the coast, this change brings some cloud and coastal showers.
Highs: 10-13

West Coast
Rain with heavy falls and possible thunderstorms / hail then easing in the evening, snow to 500 or possibly even 400m in the ranges. Blustery west to southwest winds.
Highs: 8-10

Southland & Otago
Showers about Invercargill, turning to rain in the morning as northwesterlies change strong southwest with a chance of heavy falls / thunder and hail, easing late afternoon back to showers. Some snow to 500m, lowering to 400m by evening. Otago gets similar weather but the morning may be dry then a strong southwest change moves in around midday bringing rain. Winds will likely rise to gale about coastal areas with the southwest change, perhaps inland also at times.
Highs: 7-9

By Weather Analyst Aaron Wilkinson – WeatherWatch.co.nz