T-shirts will replace puffer jackets as much of the country basks in "Australian-like" mid-winter temperatures over the weekend.
The brief warm spell comes after a windy and wet start to the week in which trees were torn up, a home was struck by a tornado and a boat ran aground on rocks.
WeatherWatch is predicting a large high off the North Island's east coast will scoop up subtropical air, pushing it down over northern areas on Friday.
Head analyst Philip Duncan said although the end of July was typically the coldest time of the year, it would be unseasonably warm for most of the North Island and some areas of the east of the South Island on Friday and Saturday.
The calm is here, the wind is coming - Your Thursday Weather Video https://t.co/9ldXgnMDtx pic.twitter.com/2q9MIyy4Tj
— WeatherWatch.co.nz (@WeatherWatchNZ) July 21, 2016
As the weekend arrives, warm air would arrive from our cousins across the ditch - and it would come directly from the deserts of Australia's interior.
Duncan said the warm air wouldn't be cooled by the Southern Ocean, as it had during a previous high, but would take a "direct flight" across the Tasman Sea, from Australia's east coast to New Zealand.
That would bring "Australian-like temperatures" across parts of the country on Saturday.
The warmest centres would mostly be in the North Island, but also in the east of the South Island, Duncan said.
While all-time monthly records were unlikely to be broken, daily records might be broken on Saturday when maximums are forecast to be anywhere from 5C to 7C warmer than average, the National Institute of Water and Atmosphere (NIWA) reported.
Several places may also have their mildest July 23 overnight on record, particularly across the North Island.
Tropical winds from north of Vanuatu would stream southward, allowing temperatures across New Zealand to rise to levels more typically experienced during late spring than mid-winter.
As air blows off the Southern Alps and ranges of the central North Island into the lower terrain to the east, it would warm considerably.
This was known as a foehn wind.
It wasn't all good news, however, as the MetService is still predicting gale force winds and rain this weekend.
With just a day of respite from the blustery winds, those heading back from school holidays on Friday will be hit by strong northerly winds which are predicted to ramp up Saturday to severe gales over much of New Zealand.
The rain is also expected to sweep up the country during Saturday and Sunday, the heaviest falls reserved for northern and western areas.
On Saturday night, total rainfall might range from 75 to 150 mm across the west of the South Island and 50 to 100 mm across the west of the North Island.
Wind gusts in excess of 150 km/h were possible in the west of the South Island, across the Cook Strait and Wellington, and for much of the western and central North Island later Saturday through early Sunday.
Winds of this magnitude may cause power outages, hazardous driving conditions, and minor structural damage.
A burst of strong winds with gusts of 80km/h to 120 km/h was forecast to come across the Auckland region very early Sunday morning.
Total rainfall might range from 75 to 150 mm across the west of the South Island and 50 to 100 mm across the west of the North Island.
From late Sunday, the rain and wind would slowly ease or clear as a narrow ridge moved on to the country.
