Keen shoppers have been queuing since the early hours in hopes of getting the best Boxing Day deals.
People are flocking to stores across the country today in search of specials - and to seek shelter, with many areas due for rain today.
But a marketing expert is warning people not to get caught up in "purchasing mania" and buy things they don't want or need.
At Noel Leeming in Auckland's Royal Oak there were about 20 people in line at opening time - 7.30am.
"I went in there and bought a coffee machine," said one man who joined the queue. "The guy was saying there were sales on pretty much everything...there were a whole bunch of families, kids, everyone."
There were queues before 7am at Sylvia Park in Mt Wellington, with The Warehouse and Noel Leeming both opening around 7am, centre manager Helen Ronald said.
The Mt Wellington shopping mall opened at 8am but several stores including Footlocker and Lush had opened early to let in their most enthusiastic customers.
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"There were big queues right across the centre. Most stores have great deals on today," she said.
"Our carparks are busy but traffic management is on there to try and make sure people can find parks as quickly as possible and make it easy for them to do their shopping."
The mall is open till 9pm, and Sylvia Park is expecting similar customer numbers to last Boxing Day - around 50,000 people.
But one marketing expert has urged caution as consumers get caught up in the whirlwind of shopping excitement.
Auckland University's senior lecturer in marketing , Dr Bodo Lang, says there "absolutely" are genuine bargains to be had.
He told Newstalk ZB's Tim Dower good bargains could usually be found in electronics, as retailers tried to get rid of old stock before new models were launched in the New Year.
Similar logic applied to bikes - with 2020 models launched in summer, 2018 and 2019 stock would often be on sale despite being in perfect condition.
"Of course there is a danger also of being lured in and buying things that may not be on sale, or where the sales advantage is quite insignificant so it's just a small reduction."
Making unplanned purchases was the biggest danger, Lang said.
"This is a really common occurrence - people get into what's called the flow, they just get into a purchasing mania and buy far more than they planned to buy."
Lang suggested focusing on the things they wanted to purchase, and searching for the best deal on those items.
"Discipline is a good thing."
The marketing industry aimed for people to get excited but there were strong regulations about what marketers could say regarding sales, Lang said.
"You can't just promise one thing and then not deliver that in store...for example you can't claim there's a significant discount when there isn't, or you can't use an artificially inflated normal price to then claim that your sales price is much lower than it actually is."