Fast Retailing Co. said Tuesday that sales at its Uniqlo casual clothing stores dropped 4.2 percent in July from a year earlier, marking the first year-on-year decline in nine months.

The sales decline was blamed on an unusually long rainy season that weakened demand for summer clothes, the company said.

The number of customers fell a marginal 0.3 percent. Sales decreased in the second half of July especially in western Japan, where there were torrential rains, a company official said.