The International Council of Shopping Centers survey of 22 major chains -- excluding the drug store sector -- found sales rose 3.9 percent in September from the same month in 2011, following a 6 percent increase in August.
The ICSC-GS survey found receipts for the week ending Oct. 6 were up 0.2 percent from the previous week.
The trade group said "a more concentrated back‐to‐school shopping season in August 2012" and changes in department store promotions helped account for a relatively strong August and "more subdued" sales in September.
"The ICSC‐GS consumer tracking survey found that overall customer traffic weakened during the past week compared with the same week of the prior year, but there were pockets of improvement at department stores, wholesale clubs, electronics stores and drug stores," the trade group said in a news release.
Weather Trends International Inc. -- which provides business with information on how weather might affect sales -- said the past week featured "the first shot of very cold air" in the United States, bringing the first snow to parts of the Rockies and north-central states.
"The sudden shock to cold weather will have sent shoppers to the stores seeking out outerwear, hats, gloves, sweaters, furnace filters, space heaters and boots," WTI said.
Gasoline prices surged last week in California, mostly due to refinery and pipeline problems, including a power outage that knocked an ExxonMobil refinery in Torrance out of commission Oct. 1. The facility was back online Friday.
The AAA said the average price of regular gasoline in California was $4.668, 22 percent higher than the national average. The average price in the Los Angeles‐Long Beach area was a record-high $4.703 Monday -- up 52 cents from the previous week and up 23 percent from the same week of 2011.
The California Air Resources Board has authorized refineries to begin producing less costly winter‐blend gasoline than scheduled to bring down the cost of gasoline.