The weekly retail tracking report released Tuesday said sales dropped 1 percent from the previous week.
Sales rose 1.3 percent from the same week a year earlier, the trade group said.
The week follows a sharp 5.4 percent week to week downturn.
"The final fiscal month of the retail year began on a soft note as weather continued to dampen the consumers' ability and willingness to shop," said Michael Niemira, ICSC vice president of research and chief economist.
"The good news," Niemira said, "is that gasoline prices were relatively steady, providing little impact on the consumers' discretionary-spending potential."