The holiday that is "Labor Day" has official significance, of course, but that first September Monday often just serves as the definitive marker that summer is winding down — or as another reminder of how much one doesn't want to labor in the first place.
In either case, annual Labor Day sales can act as a consolation prize of sorts. These typically run between the last week of August and first week or two of September (give or take a few days depending on the retailer) and offer some of the year's best prices on home stuff...