Christchurch and Ashburton are forecast to reach 27C on Tuesday, about 10C above average for this time of year. If Christchurch reaches that mark, it would be the city’s warmest day since mid-March.
But the sunny days will be short-lived.
By Thursday, Christchurch is forecast to have a high of 13C.
“Behind that front, temperatures drop off rapidly,” Martino said.
Other South Island centres are also in line for a chilly end to the week. Timaru is forecast to reach 12C on Thursday, about 4C below average, while temperatures across much of the island are expected to sit in the low teens.
The front is expected to spread north through Wednesday and Thursday, bringing rain to most of the country.
“At the moment we’re only looking at a low risk of anywhere needing warnings, but we will keep an eye on that,” Martino said.
The change is a reminder that, despite recent warm afternoons and the country’s gradual move out of winter, summer is still some way off.
“Classic spring,” Martino said, with conditions flip-flopping between warm sunshine and colder, wetter weather.
For now, New Zealanders can enjoy the sunshine while it lasts. By Thursday, many will likely be reaching for their raincoats again.