Bunnings in Cessnock, in the NSW Hunter Valley, has been forced to shut after being overcome by mould.
Customers are urged to visit nearby stores in Maitland and Singleton, or shop online instead.
The Vincent Street store closed its doors on Tuesday with no indication of when it will open again as "safety work" gets carried out on-site.
Despite the building being well ventilated, Bunnings believes the recent high volume of rain and humidity in the local area has created an ideal environment for the mould to grow.
It's believed the mould found in the store is the common type found in houses.
"Hygiene and cleaning experts" are working towards removing it, although it's unknown how long the process will take.
Bunnings regional operations manager Alan Harvey told Yahoo News Australia "the health and safety of our team and customers is our number one priority".
"Our absolute priority is supporting our team at the store and serving local customers as best as possible online, and through our nearby Maitland and Singleton stores," he added.
"We sincerely apologise to all our Cessnock customers for the inconvenience, and hope to have the store back up and running soon."
Bunnings workers are currently unable to work at the Cessnock store. Although they can be "temporarily redeployed to nearby stores" or they can "choose to take leave."
Customers react to store closure
The news was shared with some customers via a text message which said the store was closed "until further notice".
On Facebook, some people said they suspected something was wrong when they visited the store on Monday. Meanwhile, several said they'd noticed a bad smell sweep through the store.
"Was there Monday lunch time, they had plenty of fans set up and people getting around with vacuums, looks like they have a moisture problem like most people at the moment," one shopper said.
"I told you the place stunk," another wrote tagging a friend on Facebook.
Others praised the store for taking action and for putting the health and safety of staff and customers first.
But some couldn't help but think of Bunnings staff, particularly the "casual staff and the teenagers who work after school".
"[They] may not be able to work at all during the time it's closed," one person said. While another added: "I feel for the employees."
"They are doing the right thing for staff and customer's only way to go, they will survive," a third shared.
While another added: "Good to hear they are on top of it."
Some were able to see a lighter side to the news, however, with a handful of residents from the Hunter region cracking jokes on Facebook.
"I hear Bunnings sells a good mould remover," one said, an obvious nod to the store's selection of home and garden supplies.
While another mocked: "Mitre 10 will have good takings this week then."
Rain wreaking havoc on homes and businesses: 'More to come'
The extreme weather conditions earlier this month saw parts of northern NSW cop a lashing, with much of the Hunter region impacted.
This sparked fears of mould in people's homes and businesses too, which can lead to dangerous health problems, The Conversation revealed.
In a damp or water-damaged environment, toxic mould can grow and release spores that can cause health problems if inhaled.
Although parts of the area remain saturated by the recent spate of torrential rain, the Bureau of Meteorology has predicted an onslaught of rain to hit the state's Mid North coast once more.
Over the next six days, the Central Coast, Hunter, Mid North Coast and Northern Rivers regions might see up to 100mm of rain.
Rain can also be expected from Thursday until at least Tuesday next week in places like Lismore and Tweed Heads, two areas on Far North Coast of NSW which were gravely impacted by flooding just weeks ago.
Do you have a story tip? Email: email@example.com.