The owner of Dwell and Sofa Workshop says shoppers have been kept out of its stores because of the hot weather, and the fall in earnings has also been blamed on "disruption" to ships bringing supplies from Asia.
Like-for-like revenues have fallen about 4% over the 49 weeks to 7 July, the company said.
Analysts had been expecting earnings before interest, taxes, depreciation and amortisation (EBITDA) of £84.51m for the year ending July.
However, in a statement, DFS said it anticipates EBITDA for the full financial year will be below the £82.4m reported in 2017.
EBITDA is a measure of profitability that companies prefer to use while they are going through periods of change, usually because they have acquired new businesses.
The UK's biggest independent furniture retailer, which bought smaller rival Sofology for £25m, is struggling amid a slowing housing market, tighter credit conditions and a squeeze in household budgets.
DFS said: "We continue to expect that the furniture retail market will remain challenging over the next 12 months, given ongoing reduced consumer confidence levels, although we would expect some alleviation of current short-term demand effects.
"Our previous investments in our supply chain and the recent acquisition of Sofology, together with progress expected at Dwell and Sofa Workshop, will provide benefits to earnings that we expect to help mitigate the challenging sales environment."
In March, it reported a 58% fall in pretax profit to £7m in the first half of the year. That included £4.6m in costs and charges related to the acquisition of Sofology and upmarket brand Multiyork.
While a recent hot spell has helped some British retailers, the Confederation of British Industry warned in late June that clothing stores and furniture shops were reporting a fall in sales.