Public health authorities are warning people about the effects of the heat as temperatures put New Zealand on target for its hottest month to date.
MetService says anti-cyclones in February have heralded humidity levels usually experienced in the tropics. Temperatures have peaked at two or three degrees celsius higher than normal.
The National Institute for Water and Atmospheric Research says some records have been broken over the past fortnight and climate change and the La Nina weather pattern are largely to blame.
Senior climate scientist Georgina Griffiths says the records include 41.3 degrees celsius recorded in Timaru in the South Island on 6 February.
However, it is likely the La Nina weather pattern has peaked and temperatures will now start to fall, she says.
The hot weather has prompted the Auckland Regional Public Health Service to ask people to check on elderly neighbours or relatives. It warns the young, elderly and the sick to stay out of the sun, drink water and avoid exertion.
Zoos are using iceblocks of frozen food and sprinklers to cool some animals down.
Hamilton zookeeper John Ray says the animals are reacting in the same way as humans to the high heat and humidity, with monkeys acting as though they are sunbathers at the beach.