New Zealand is being warned to brace for a good ol' fashioned Autumn sou'west flow with Friday seeing cooler/colder weather spreading across the country.

WeatherWatch says windy south to south-westerly winds (which may be more nor'west in the north ahead of the change) are aslso on the cards.

"Showers, some heavy and squally off the Tasman Sea, will spread into western areas but it comes from out of the Southern Ocean region - so it's got a bit more 'wintry bite' to it," says the weather organisation in its latests update.

"The North Island won't have so much of the cold air though - it's primarily over the South Island.

"Higher elevation snow and low level rain continues around the south and west of the South Island."

As for Saturday - powerful high pressure starts to move in from Australia and will still mean a few showers along the western coastline (sometimes they sneak in even if not blatantly forecast, as sou'westers at this time of year tend to be cloudier and more showery than they do in the months of the year with longer daylight hours).

Winds ease further on Saturday which means it will be a cold start - frosts are possible through the interior of the South Island. View general frost maps here and drill down deeper using our new New Zealand Weather App to see Frost Graphs for your hyper-local part of NZ (free) ... or to set up your own frost alert push notifications (paid).

On Sunday high pressure crosses NZ properly and winds ease for many regions and most (but not all) showers will clear. Again, a few light showers may remain along the western side of NZ (including Auckland) with cloudy areas.

Westerlies develop in the south of the country whilst easterlies form in the north.