Heatwave weather: New Zealand could hit 40C temperatures

New Zealand's boiling-hot weather could be about to get even more heated - with areas hitting 40C as a searing blast of burning air out of Australia pushes temperatures to new heights.

On Friday, Gisborne sizzled under 38-degree heat - the hottest day in New Zealand this summer and its highest temperature since the records began in 1940.

But this is just the beginning, with experts warning the brutal Australian heatwave heading our way hasn't even hit our shores yet - and things are only going to get worse.

WeatherWatch warns the scorching wave of air coming across the Tasman moves into the South Island on Saturday, then across the North Island and upper South Island on Sunday, Monday and Tuesday.

"New Zealand's highest temperature's don't often occur on a calm day, it needs a nor'west flow out of Australia and with that still to arrive it boosts the chances of climbing to 40C," says WeatherWatch head forecaster Philip Duncan.

"Under the right conditions, we do have the ingredients for some isolated parts of eastern New Zealand to reach 40C in the next 72 hours."

WeatherWatch says the Gisborne region will bear the brunt of the blast, probably on Monday when the heat peaks over New Zealand - as valleys in the east can enhance the heat, especially when timed with clear skies.

"On the western side of the island and towards the north places like Auckland will get more warmth with daytime highs possibly reaching 30C inland," WeatherWatch warns.

"Add on top of that Auckland and other northern centres will have humidity between 65 and 95 percent in the days and nights ahead, making it feel another 4C or 5C warmer than it is. So yes, it will feel like the low to mid-30s at times."

New Zealand's current temperature record is 42.4C, set in Rangiora in 1973.