The ICSC-Goldman Sachs weekly tracking report indicated sales "skyrocketed by 3 percent on a sequential weekly basis."
Sales also rose 2.9 percent compared to the same week of 2012, the report released Tuesday said.
The report noted that retail business was "very strong at grocery stores, department stores and specialty retailers ... but other segments showed healthy improvement as well."
Summer clearance sales helped boost customer traffic, the report said.
On the other hand, "weather impacts ... were mixed," as heat was "scorching" in the West, cool in the Midwest and humid and warm in the Northeast.
Gasoline prices were little changed in the week, dropping a "marginal 0.4 cents" per gallon to a national average of $3.492 on Monday, the Energy Information Administration said.