"It may well be that there are some bargains to be had towards the end of the season, but things could change, we're only a month into winter, we've still got July and August to go."
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Benje Patterson, economist at Infometrics, said data showed people were spending less on winter clothes in New Zealand.
"Some of that can be down to the fact that the weather has been warmer, so people haven't been purchasing as many heavy winter coats and so on, but there's also other factors that are constraining the value of what's being spent on those goods," he said, citing the high New Zealand dollar and online purchases falling under Customs' tax threshold and therefore not being recorded.
However, retailers themselves said while winter-specific items had not been selling so well, overall sales were good.
Farmers managing director, Rod McDermott, said the department store's June sales were "comfortably ahead of last year".
"Certainly the mild conditions and late arrival of cold weather has meant sales are lower than normal for winter-only type products in June," he said.
"Not much of a concern as winter and the cold do always arrive in New Zealand."
A spokeswoman for The Warehouse said it had "been impacted by unusual and sustained warm temperatures to date this autumn and winter".
"As a result, while sales are still above last year, sales of seasonal apparel and home products, have been affected."
James Logan, director of heatpump retailer Energy Efficient Solutions, said it had seen less interest from potential buyers.
"This June we had 35 per cent less leads than we normally get, but sales were up 20 per cent.
"Lead volume is almost directly attributable to the season. It's the mildest winter we've had since we've been in business [since 2011]."
John Harris, owner of City Firewood in Christchurch, said the mild weather had "made a difference".
"In the last two or three weeks, it's been busy, but definitely a bit quieter than it would be if it was snowing," he said.
However, the polar blast predicted to hit this week had seen an increase in sales yesterday.
"Winter sales are very spontaneous sales, if [people] anticipate cold weather they freak out and come and buy."