"It's looking into the 20s for most places, it will be a little bit cooler," Kerr said.
"The band of warm air will trend north and hit Bay of Plenty with places like Whakatāne and Keri Keri hitting 30C."
Some drizzle was expected around central New Zealand during the day, he said.
Looking ahead, the ridge of high pressure moving north over the country would continue during Wednesday as a front approaches New Zealand from the southwest before moving north across the South Island on Thursday.
The front would bring rain to western districts of the South Island, possibly reaching warning criteria in Fiordland, Westland and Otira.
"A ridge pushes in over the South Island late Thursday and Friday as the front moves onto the North Island and weakens," Kerr said.
The National Institute for Water and Atmospheric Research was forecasting little to no rain in the North Island this week and any meaningful rainfall would be confined to the South Island's west coast.
It also spelled warm weather for the North Island and a cold snap in the South Island later in the week.
Your weather
Whangārei: Fine with southwesterlies
High 28C Low 17C
Auckland: Fine, some morning and evening cloud. Southwesterlies.
High 26C Low 17C
Tauranga: Fine westerlies.
High 29C Low 16C
Whanganui: Morning cloud and chance shower, becoming fine afternoon. Northwesterlies.
High 24C Low 14C
Napier: Fine, cloud increasing from afternoon with a chance of shower. Northwest changing southerly morning.
High 28C Low 17C
Wellington: A few showers developing with a morning southerly change, clearing afternoon as winds die out.
High 22C Low 15C
Christchurch: Early low cloud and drizzle, then fine. Northeasterlies developing afternoon.
High 21C Low 12C
Dunedin: Mainly fine, but evening cloud and isolated showers. Afternoon sea breezes.
High 22C Low 12C
