Scorching temperatures left holidaymakers sweltering on the last day of the summer break for many, with icecream-melting highs in the mid-30s in Canterbury yesterday.
MetService duty forecaster Chelsea Glue said summer was "definitely here" as most of the country basked in the heat yesterday.
The hottest recorded temperature was at Lake Pukaki in the South Island, where temperatures soared as high as 35.2C.
A spokeswoman for the Twizel Holiday Park, 23km away from Lake Pukaki, said the heat had left holidaymakers searching for shade.
She said most people had spent the day at Lake Pukaki boating, swimming and enjoying other water sports.
"It's hot, people have been looking for shade ... it has definitely been the hottest day so far," she said yesterday.
Most of Canterbury experienced the sizzling weather, with Hanmer Springs reaching a high of 34.2C and Ashburton topping out at 33.7C.
"We have a ridge of high pressure over top of us at the moment bringing classic summer weather ... lots of clear skies and light winds," Ms Glue said.
"It was definitely the hottest day of the summer for Canterbury so far, but it has been very nice for most places. Summer is definitely here."
Weather was varied for those spending times at other holiday hot-spots yesterday.
In Whitianga, on the Coromandel Peninsula, temperatures reached 22C, although there was some cloud and showers.
In Russell, in the Bay of Islands, temperatures reached a high of 24C.
In Auckland, people flocked to beaches to enjoy the clear skies and a high of 25C.
As many people return to work today, a front will move on to the lower South Island, bringing with it cooler temperatures and some rain, Ms Glue said.
"This means the temperatures won't be quite so hot, and it will bring a bit of rain and a bit of cloud to the South Island."
Most of the North Island will have a fine day, apart from some areas of cloud and a few afternoon showers for those in the north.
Although the fine weather will move across and away from the North Island early this week, leaving clouds and a few showers in its wake, the fine weather will be back from the middle of the week.
"The [front] will move over the North Island, weakening as it goes, so it will bring increased clouds and a few showers and then it will gradually move off," Ms Glue said.
It would be replaced with another ridge of high pressure which would bring fine weather to the South Island from tomorrow and more sunshine to the North Island by Wednesday.
"The high will spread over the North Island and bring some nice settled weather for Thursday and Friday."