A northeasterly airflow increases over the South Island on Wednesday, while the North Island sees a ridge in the morning, then northeasterlies increase from afternoon. Meanwhile, a front moves towards the west of the country from the Tasman Sea, making landfall in the evening.
The North Island starts the day with a light frost inland, perhaps even a touch of fog, then becoming mostly cloudy. Rain moves into Northland in the afternoon then spreads elsewhere in the evening. Rain may become heavy later on / overnight. Gisborne through to Wairarapa may start the day with some sun then expect thickening high cloud, with a few spots of rain later in the evening.
For the South Island, expect mainly cloudy skies everywhere, with rain in the west, heavy at times from late afternoon / evening. The East Coast has the odd drizzle patch then some evening rain.
Northeasterlies about coastal parts of the West Coast and the East Coast of the South Island are gusty to strong at times from afternoon and through the evening.
– Aaron Wilkinson, WeatherWatch.co.nz