The International Council of Shopping Centers said sales fell 0.3 percent compared to the previous week, but rose 4.2 percent compared to the same week of 2011.
The trade group said shoppers took a break for the week.
"Over the past week, the ISCS-GS consumer tracking survey found consumers were shopping less overall as a markedly higher percentage of consumers reported they did not shop at all during the [reporting] period," the report said.
The trade group said shopping was temporarily interrupted by "a late season Nor'easter, [which] swept up the East Coast early in the week bringing heavy rains and wins to the coastal cities form Florida to Maine."
While the weather got in the way of some shopping, gasoline prices fell for the fourth consecutive week, averaging $3.83 per gallon on April 30, a drop of 5 cents from a week earlier, the Energy Information Administration said.