Much of the country has already had a warmer than average week by day but both Thursday and Friday will be warmer than average in every region of New Zealand.

WeatherWatch.co.nz says with the exception of Nelson and Marlborough the entire South Island is about 4 to 8 degrees above normal for this time of the year this afternoon while on Friday every single South Island region will be in that category.

Much of the North Island is heading in the same direction with Friday looking even warmer and at least half of the island 4 to 8 degrees above normal by day.

Many places today and tomorrow will have afternoon highs in the low 20s while Hawke’s Bay has the chance of reaching 23 to 25 degrees on Friday, which is exceptionally warm for the second week of May.

The reason? Sub-tropical and Australian northerly airflows across New Zealand. There is a cool down coming though – it arrives in south eastern Australia today and reaches New Zealand this weekend in the south and nationwide by Sunday. It will bring cold weather to the lower South Island from Sunday and while northern NZ will lose a few degrees off the daytime highs the upper North Island will be least impacted by the cool down next week.

– WeatherWatch.co.nz