A strong northwesterly airflow lies over New Zealand today, a cold front moves into the lower South Island this morning then moving northwards reaching the lower North Island overnight.

Northland, Auckland, Waikato & Bay Of Plenty
Sunny areas and increasing cloud, the odd shower spreads into the Waikato during the afternoon and one or two may reach Auckland in the evening. Bay Of Plenty is mostly sunny in the morning then cloud becomes more frequent from afternoon. Breezy westerlies.
Highs: 17-18

Western North Island (including Central North Island)
Cloudy with the odd shower, rain moves in overnight. Gusty northwesterly winds.
Highs: 14-16

Eastern North Island
Sunny areas and increasing high cloud, northwesterly winds. Overnight rain moves into Wairarapa with a southerly change.
Highs: 18-21

Wellington
Cloudy, the odd spit in the north (Upper Hutt etc) then overnight rain as strong to gale northwesterly winds change southerly.
High: 16

Marlborough & Nelson
High cloud, strong northwesterly winds gusting to gale at times (more so about Marlborough and especially the Sounds). Rain moves into Nelson in the evening then overnight for Marlborough with a southerly change.
Highs: 18-20

Canterbury
High cloud and some sun, heavy rain in the high country, chance spot of rain elsewhere otherwise mainly dry. Warm temperatures nearer the coast. Late evening widespread rain as gusty northwesterly winds (strong inland with gales possible) change southerly. Snow lowers to 500m overnight.
Highs: 16-21

West Coast
Rain with heavy falls, easing evening as gusty northwesterlies change southwest.
Highs: 12-14

Southland & Otago
A cold front pushes into Southland during the morning then Otago in the afternoon bringing rain. Rain eases to showers once the front pushes through, these showers may be heavy with small hail then clearing away during the evening. Expect showers before the front moves in for Southland and some rain about western Central Otago, coastal Otago is dry in the morning. Snow lowers to 500m before clearing evening. Northwesterlies change fresh cold southwest with the front.
Highs: 12-16

By Weather Analyst Aaron Wilkinson – WeatherWatch.co.nz