In a season first today, MetService has issued heat alerts to known hotspots around the motu, warning residents to take care as temperatures hover around 30C.
The weather service issued the alerts for the top of the South Island and parts of Hawke's Bay, with the temperature in Blenheim expected to peak at 31C and Nelson at 28C, while Napier was forecast to hit 29C.
MetService began issuing heat alerts for 46 towns or cities in 2021 when forecast temperatures were expected to be unusually hot.
Meterologist Mmathapelo Makgabutlane said Wednesday's warnings were the first for the 2024-2025 season.
She said the trigger for the alert came when temperatures tipped into the top 1 percent for that area.
"We are now in summer, and it has come out in full force. We've had hot temperatures for the last few days, especially in the eastern parts of the country, and that does look set to continue today, Wednesday.
"For the heat alerts, we're really looking at temperatures that are more than just your typical hot summer's day."
Makgabutlane said while some areas were already hitting 30C during the day, it was the overnight temperatures contributing to the unusual highs.
"Those temperatures remain warm throughout and because of that, we currently have some heat alerts.
"The areas that we are looking at include places like Blenheim, Napier and Hastings for those hot daytime and hot nightime temperatures."
She said the alerts were a warning to vulnerable groups - who were more likely to be affected by temperatures spikes - such as the elderly, very young, and those on medication.
Metservice was anticipating a hot summer, and would keep its website updated regarding heat alerts.
It recommended people in hot areas stay out of the sun and keep hydrated with plenty of cool drinks.
For those who were feeling unwell, it was important to rest and rehydrate.