Cooler temperatures about to hit

Cooler temperatures are on the way. Photo / Thinkstock

The dog days of summer are on their last legs. Cooler conditions are forecast for today following a three-day spell that marked the warmest week of summer so far.

Some regions experienced their highest temperatures in three years - on Wednesday, Palmerston North reached a high of 32C, its hottest day since January 2011. Hurunui in Canterbury hit a high of 34C, and in Christchurch, the temperature reached 33.3C on Tuesday.

For three days in a row, the mercury in Masterton topped 30C - from 30.4C on Wednesday to 31.4C on Friday.

The Wairarapa town's average summer high is just 24C.

And bedclothes became surplus to requirements as Auckland sweated under high humidity all week - but frisky southwesterlies will push the moist Auckland air out of the way today, the MetService said. Showers in the upper North Island would clear this morning, and fine spells would increase.

WeatherWatch head analyst Philip Duncan said airflow from subtropical regions north of New Zealand caused the intense humidity.

"It's the reason we've experienced the hottest weather so far this summer," he said.

"Certainly in Auckland, it felt like the hottest week of the year because the humidity and heat were combined for the first time this summer."

Duncan said humidity in Auckland and its surrounds would decline today and tomorrow, but likely rise again mid-week.

Temperatures would be in the low to mid 20s, down from their high of 28C, and overnight lows would be around 14-15C, down from 20C this week.