A front races northwards over the South Island this morning then pushes northwards over the North Island this afternoon / evening, all in a strong westerly quarter airflow.

Northland, Auckland, Waikato & Bay Of Plenty
Risk of a shower, showers more likely from late afternoon then evening rain. Some sun at times mainly morning. The Bay Of Plenty stays dry for most of the day, not till evening are showers more likely. Breezy Westerly winds.
Highs: 15-18

Western North Island (including Central North Island)
The odd shower then rain develops in the afternoon with possible thunderstorms, west to northwesterly winds strengthen rising to gale at times about coastal areas after midday.
Highs: 11-16

Eastern North Island
Mostly sunny with northwesterly winds strengthening, possibly gusting to gale at times about the Wairarapa from afternoon. The Wairarapa sees cloud thicken up in the afternoon and the odd spot of rain may spread from the west.
Highs: 15-18

Wellington
Some morning sun then a few showers develop in the afternoon as northwesterly winds rise to gale.
High: 15

Marlborough & Nelson
Mostly sunny, northwesterlies strengthen in the afternoon bringing some cloud. Showers from afternoon for Nelson, only a few spots of rain may pass over into Marlborough for a time.
Highs: 12-15

Canterbury
Dry at first with some sun, late morning cloud thickens with a few spots of rain possible as gusty Westerlies develop. Sun then breaks through again in the afternoon. About the high country (inland mountains west of the foothills) expect rain to spill over from the west with snow lowering to 600m.
Highs: 10-15

West Coast
Morning rain, possibly heavy then easing to showers. Showers may still continue to be heavy at times for the rest of the day, perhaps even a thunderstorm or two with small hail. Snow lowering to 500m to most areas by evening. Gusty westerly winds.
Highs: 9-12

Southland & Otago
Showers, some may be heavy at times with a chance of hail. Snow flurries to 500m. Showers becoming much less frequent about inland Otago in the afternoon, clearing evening. Showers clear near the coast in the afternoon with sun then possible. Brisk westerly winds tend southwest overnight.
Highs: 8-11

By Weather Analyst Aaron Wilkinson – WeatherWatch.co.nz