Next has said that the "unseasonably" warm September has had a detrimental effect on sales and says that it could be exacerbated if the warmth continues.
The British retailer had expected sales growth of 10% for its third quarter, but after a warm start to autumn this currently stands at 6%.
"Cooler weather in August resulted in several very strong weeks. However, warmer weather in the more important month of September has had the reverse effect," it said in a statement.
It says that if the warm weather continues, it may be forced into lowering its profit forecast which currently stands at between £775m and £815m.
The hot September has meant that consumers have delayed buying their clothes for the winter months, which most stores now have in stock.
M&S, House of Fraser, New Look and Debenhams have all began offering discounts already on their new seasonal ranges.
Next shares fell by more than 3% in early morning trading to 6,603.20p.