Temperatures are expected to reach 31C in Christchurch, 25C in Blenheim, 26C in Dunedin and 24C in Queenstown.
MetService is forecasting it will not get below 20C in Christchurch on Tuesday night.
The one place that will seemingly miss the warm weather is the West Coast of the South Island, which will have spots of rain throughout Tuesday, Bakker said.
A high of 21C is expected in Greymouth.
As well as warm temperatures, high winds are also forecast for most of the South Island, meaning fire crews are on high alert.
A strong-wind watch is in place for Fiordland, Southland and the Queenstown-Lakes district from 9am on Tuesday to 7am on Wednesday.
"North to northwest winds may approach severe gales in exposed places," Bakker said.
There is also a warning in place for the Canterbury High Country, starting from 6pm tonight until 1pm on Wednesday.
A post on the Canterbury FENZ Facebook page said firefighters were battling a large fire in Rangiora this morning ,where temperatures had already reached 20C by 7am.
"Winds are expected to reach gale force, so if you have had a permitted fire in the last couple of weeks (other than crop stubble) we ask that you check the piles and ensure they are extinguished. As the wind is likely to stir something up.
"Reminder that permitted or approved fires are not to be lit in high winds," the post said.
