Supermarket opening hours vary across the country — but on weekdays they’re typically from mid-morning until sometime in the evening.
On weekends, you may find slightly reduced hours or earlier closing times in smaller towns. New Zealand cities tend to have supermarkets that generally open earlier and close later. Use Google Maps to find the supermarket closest to where you are — then click on the link for opening hours.
You may also find the occasional convenience store in touristy areas like Queenstown open 24 hours a day.