The shop would be open seven days and stock produce, meat, seafood, dairy, baked and dry goods, beer and wine at normal Countdown prices. It was due to open on August 1.
The company was still in talks with the landlord, but if it did have to close the Puketona Rd store it would offer online shopping with no delivery charges as long as there was no full-service supermarket in town.
Ms McNaught hoped all staff could be retained, either at the temporary shop or the Kerikeri and Kaikohe supermarkets.
If the company was able to stay at Puketona Rd it would decide in mid-July what to do with the fire station.
Far North Holdings chief executive Andy Nock said he was pleased to be able to help a business that employed many people and provided an essential service.
The company had owned the 230sq m fire station since a land-swap with the Fire Service in 2011 and it had been up for lease since 2013.
It was to have been converted into a cafe and bar but that is now on hold.
A group had been hoping to convert it into a community centre offering youth and arts activities.
Countdown's lease will be for one year initially but with rights of renewal.
Paihia's only other sizeable grocery store is the Four Square on Williams Rd. Apart from Haruru Falls, about 4km inland from Paihia, undeveloped commercial land is in short supply in the area.