As temperatures are expected to surpass 30degC again in some areas on Tuesday, vulnerable elderly people are being reminded to keep cool and hydrated.
Beaches across the country were packed on Monday as warm air from Australia blew across the country, with Hawkes Bay hitting a high of 37degC and the Marlborough Sounds reaching 36degC.
- New Zealand heatwave: Kiwis warned to drink less alcohol or risk hospitalisation
- Weather: New Zealand's hottest areas hit 37degC
On Tuesday, inland areas can expect hotter temperatures than on Monday, with WeatherWatch warning the top of the North Island, Waikato, and parts of the central plateau will likely surpass 30degC.
In the South Island, Marlborough, Nelson, the West Coast, Southland and Otago may also reach 30degC.
The warm weather has prompted a reminder from Age Concern chief executive Stephanie Clare for the public to keep an eye out for elderly people who may become vulnerable in the heat.
"[Make sure] they have got drinks that are acceptable to them, that they have got an ice block or something else that will cool them down," said Ms Clare.
"Make sure they are staying hydrated, they are still taking their medication. Don't stop those at any time."
She also said it can be simple things like a cold flannel or keeping the curtains drawn to keep the sun away that can help in the hottest times of the day.
The reminder comes on the back of a warning from Canterbury District Health Board medical officer of health Alistair Humphrey that too much alcohol during warm temperature can lead to heatstroke.
Alcohol interferes with the regulation of water levels in the human body, causing you to urinate more. As your body runs out of water, dehydration may set in, causing headaches, dizziness and confusion.
"If someone's not wearing a hat and they're in the sun, or if you think someone's not drunk enough water - or, in particular, if you think they've had too much alcohol, because that will also dry you out - I think a bit of friendly advice can often stop someone from ending up in the emergency department," said Mr Humphrey.