MetService is warning Aucklanders Friday could be one of the hottest of the year and urging them to "seek shade" amid predictions temperatures across the motu could soar past 30C again at the weekend.
The official temperature in Auckland was 21C as of 8:30am and was set to top out 26C by 4pm, MetService said.
"The temperature is forecast to be very hot for this location," said MetService's heat alert.
Auckland's forecast showed it would be "uncomfortably warm and muggy" in the city on Friday.
"We advise you to keep hydrated, seek shade, check in with vulnerable people and look after your pets & livestock," the warning on the MetService website cautioned.
"Extreme heat during summer can be draining and have an impact on people's daily lives - especially their health and wellbeing. Everyone is vulnerable to extreme heat," MetService said.
On Thursday, the maximum temperature in New Zealand breached 33C in south Canterbury.
The Canterbury region was set to record temperatures in the mid-20s again on Friday, before climbing back to the 30s on Saturday.
New Zealand is currently being influenced by the El Nino weather pattern, which is associated with warmer ocean surface temperatures caused by wind pattern disruption.
On Thursday, MetService said it expected high temperatures to persist across the weekend.
"MetService advises anyone out and about in the sunshine over the next few days to remain sun smart: slip, slop, slap, and wrap, and make sure you have sufficient fluids to keep you hydrated.
"Heat alerts will be issued for locations that are reaching their highest temperatures - keep up with your local forecast to make sure you are the most prepared you can be for the day."
