August is "warmer than usual" and temperatures are not expected to cool anytime in the near future, the MetService says.
Taupo, Gisborne, Te Kuiti and Palmerston North are just a few of the cities to experience balmy overnight conditions so far this month.
MetService duty meteorologist April Clark said most of the country was enjoying temperatures on average up to 4C warmer than usual for this time of year.
Aucklanders woke to a pretty average August of 10.3C today, but towns like Blenheim are where the impact is really being felt.
Clark said the town had just got off the back of enduring down to -5C during the bitterly cold last two weeks of July, which were colder than usual.
But this morning, like the week so far, it reached 4.5C.
"It has been, on average, warmer, especially than what we have been having. The last couple weeks of July, pretty much almost every main centre was colder than average. So maybe that's why it's feeling so warm."
Although up to 4C warmer overnight "wasn't a huge amount" it covered the whole of the North Island and upper South Island.
"That's just the northerlies bringing warmer air in."
And it was set to continue with similar weather forecast over the weekend.
"Taupo, Gisborne, Thames, Whitianga, Te Kuiti, Wainuiomata, Palmerston North are looking warmer than average over the next couple of days.
"There's more cloud about, which helps keep any warmth [from] radiating out at night. It directs it back down so we don't lose quite as much heat in the evening and overnight."
The only downside to the northerlies was the wet weather.
"There's always a downside."
MetService's Georgina Griffiths already predicted "warm and wet" weather for most regions in her monthly forecast on its website.
However, the country's eastern regions - Gisborne down to Otago - would cop a fair amount of rain but it would be in the "near normal range".
"Temperatures in August are typically very changeable. However, the monthly average temperature is forecast to be slightly warmer than usual (average to above average) for most of the country.
"The notable exception is inland Southland and Otago, where near average temperatures are predicted."