Weather: South Island gripped by high temperatures as heatwave shows its force

As most Aucklanders enjoy a day off work the rest of New Zealand is facing a sweltering start to the working week.

It's hottest in central Otago where Alexandra currently has a temperature of 30.5degC.

However it's expected to get even hotter, MetService is forecasting temperatures of 34degC in Wanaka, while nearby Alexandra should hit 35degC.

In other main centres it is expected to hit the high twenties and low thirties. Aucklanders can expect 29degC while Hamilton has been forecast 30degC and Wellington is expected to reach 28degC.

In the South Island Christchurch is expected to reach a balmy 25degC while Dunedin will reach 27degC.

According to MetService it looks like a beautiful day in Wanaka but residents should be careful as the weather has a darker side.

"Another scorcher expected down south, Alexander expected to reach 35C and Wanaka 34C," the forecaster said.

"A great day on the cards but it will be very hot this afternoon so remember to stay hydrated and slip, slop and slap."

The Chief Coroner issued a warning about the weather last week after a Christchurch woman with MS died of hyperthermia.

The weather could reach up to 40degC in some places and is not expected to lessen until Wednesday, however the end of the heat can bring its own problems with heavy rain forecast to hit NZ.