Much of the country is in for some hot sunny days this week, with some South Island towns getting 30C temperatures.
The South Island will have the most unusually warm temperatures compared to the average for the time of year, despite chilly starts to the day.
North Island centres are also forecast to also get to the mid- to high-20s.
MetService meteorologist Tui McInnes said the high pressure system would help keep conditions calm and clear, allowing temperatures to warm up during the day with places in the Canterbury Plains and Central Otago reaching 30C plus.
Blenheim is due to reach 30C today, but is forecast to drop to a brisk 9C overnight.
Alexandra will have 26C today before getting to 30C tomorrow, and Ashburton is forecast to break into the 30s tomorrow with a maximum 31C.
Auckland is due to have a high of 25C, matching yesterday's hot weather for the Round the Bays event, and will drop back to 23C tomorrow.
Hamilton is due to be slightly warmer with 28C today and reach 25C tomorrow, while Napier is forecast to have 25C both days.
In the capital, 21C is likely for today and tomorrow. Tuesday.
Christchurch would have 28C for both today and tomorrow and could get to 29C on Thursday.
After a 23C day today, Dunedin is forecast to have 28C temperatures tommorrow and hit 27C on Thursday.
Queenstown is due for a relatively mild 22C today but the resort town would get to 26C tomorrow.
But as a reminder that it is actually autumn, overnight temperatures are cool.
The coldest place this morning was just south of Waiouru with -0.6°C, MetService said.
The hot temperatures in the east of the South Island will give way to a new weather system towards the end of the week, which will bring some rain to northern and western parts of the country.