The so-called heatwave took its time coming to Dunedin yesterday with a sea breeze preventing the city from getting much above 20degC during the day.
However, things got hot at night.
Temperatures peaked at 2am and later on Dunedin remained the hottest place in the country at 8.30am at 25.8degC.
MetService meteorologist James Millward said the balmy conditions were caused by a northwesterly, which came through bringing warm air off the Southern Alps.
But Mr Milward said the high temperatures would not last, as a southerly, which is also bringing damaging winds to parts of the South, sweeps through.
"It's going to feel pretty cool."
Mr Milward's predictions proved correct and by 10.40am the temperature had dropped to 14degC.
Temperatures in Gore dropped from 21degC at 7am to 11.4degC at 8.30am.
Meanwhile, while people throughout the country were working out how to cope with a predicted heatwave this week, those in the hottest part of Otago were unfazed by the weather.
Central Otago Mayor Tim Cadogan said residents seemed to be coping, and he had heard no complaints about the heat.
"While this might be a heatwave for the rest of Otago, it's simply just summer for Central Otago, and not a big deal."
Central Otago was the hottest region in Otago this week, but no Otago regions achieved "formal heatwave status", a MetService spokesman said.
A heatwave is defined as when the daily maximum temperature exceeds the average maximum temperature by five degrees or more for five consecutive days.
It was not just Central Otago sweltering yesterday.
Official MetService and Niwa data showed Dunedin Airport, Mosgiel, Clyde, Alexandra, Wanaka, Middlemarch, Ranfurly and Gore all broke 30degC.
A MetService meteorologist said Dunedin City had a high of 22.4degC at 11am, before a sea breeze kicked in and kept temperatures in the city from reaching the highs inland.
The high for the southern region - 33.6degC - was recorded at both Clyde and Middlemarch at 3pm.
However, relief is on the way.
MetService said rain was expected for much of the region today, and temperatures would sit in the early to mid 20s.
Due to the forecast rain, the NZ Transport Agency urged drivers to be wary of possibly hazardous "summer ice" on South Island roads.
"There is some rain forecast across the country, and after an extended run of hot summer days, we may start to experience slippery road surfaces, sometimes known as summer ice," journey manager Lee Wright said.
"Even a very small amount of light rain can make the roads very slippery. In fact, it can be more hazardous than heavy rain, because grime and exhaust particles that have built up on the road take longer to be washed away."
Fire and Emergency NZ also warned residents in Otago and Southland to ensure old fires were totally out, as they could reignite in strong winds - a severe wind warning was issued yesterday for this morning for Southland, Fiordland and Stewart Island, and a strong wind warning for Coastal Otago from Dunedin northwards.
The fire risk is high across Central Otago, and moderate in coastal Otago.
A restricted fire season is in place in Dunedin, Clutha, Central Otago and Queenstown Lakes.
