Parents dreading the expense of back-to-school shopping this year put it off until the last minute with some national retailers reporting that their August results got a late boost as school bells finally started ringing.

It wasn't enough to bring up overall results. Sales at established stores operated by almost 40 chains would have been relatively flat without an assist from massive retailer Wal-Mart. Including a 2.8 percent same-store sales increase at the Bentonville, Ark., chain's established locations, retailers managed a 1.7 percent increase, according to the International Council of Shopping Centers, an industry trade group in New York.

"The slower-than-trend August sales pace was touched by weakness in the economy, cold and wet weather, a later start to the school year and lean inventories," said Michael P. Niemira, the group's chief economist and director of research, in a written analysis.

Consumers have seen some relief from high gas prices at the pump in recent weeks, but food prices continue to rise; and the caution that has become a part of many family budgets is still evident. Following a trend set over the past few months, consumers seem to be trying to buy only what they really need and only when they really need it.

Target, which reported a 2.1 percent same-store sales drop, noted strong sales of nondiscretionary health and food items, while Costco Wholesale Corp., with its 9 percent gain, said the food side of the business had been strong.

Meanwhile, South Side-based teen retailer American Eagle Outfitters ended the month with a 5 percent decrease in same-store sales, but that was better than it had been doing a week earlier. The company said promotional pricing on jeans and T-shirts helped.

J.C. Penney's, which had a comparable store decline of 4.9 percent, reported improvement toward the end of the month and cited shoppers choosing to shop later in the back-to-school season.

"As with other seasonal events, customers are shopping closer to their needs," said Eduardo Castro-Wright, president and chief executive officer of Wal-Mart's U.S. operations, in a monthly sales update. "With many more schools opening later this year, overall business accelerated at the end of the month."

TJX Companies, which operates the T.J. Maxx and Marshalls chains, geared its back-to-school marketing toward September.

"Retail sales are being hurt by shoppers spending less on back-to-school and by the diminishing impact of tax rebates," said Frank Badillo, senior economist at TNS Retail Forward, a consulting group in Columbus, Ohio, that also assembles a monthly analysis of the data released by retailers.

The pullback by consumers even touched luxury retailers that are sometimes seen as being less vulnerable to economic turmoil because they cater to a clientele with deeper pockets. Nordstrom reported a 7.9 percent dip in same-store sales, and Saks had a 5.9 percent drop.

Retailers tend to view the late summer season when students are heading back to the classroom as an early indicator of how consumers will feel about spending by the time the critical holiday season begins. A steady string of tough months already has many stores trimming inventory levels so they won't have to take a lot of markdowns later.

The shopping centers council is projecting that September sales will rise about 2 percent. In the short term, hurricanes could disrupt things a bit. Some retailers have already lost sales days to storms, and others warned the next weeks could see more hits from the weather.