Meanwhile, the number of people filing new claims for unemployment benefits dropped last week to the lowest level in more than three years, a promising sign that companies feel better about the economy's prospects and are less inclined to get rid of workers.
The robust sales figures, released by retailers early Thursday, cut across industry sectors, even some of the long-struggling department stores.
"The month will be the strongest of the year so far," said Michael P. Niemira, chief economist at The International Council of Shopping Centers.
He said the International Council of Shopping Center-UBS sales tally should be up 6.5 percent in March, compared with a 0.2 percent decline in the year-ago period. The tally is based on what the industry calls same-store sales, those from stores open at least a year. They are considered the best measure of a retailer's health.
He added that warmer weather helped retailers earlier in the month, though sales decelerated in the last week when conditions turned cooler.
Wal-Mart announced a 6 percent gain in same-store sales, while analysts surveyed by Thomson First Call expected 5.7 percent. Total sales rose 14 percent.
Costco said same-store sales were up 11 percent, surpassing the 8.2 percent projected by analysts. Total sales were up 14 percent.
Department stores and mall-based apparel stores reported consumers responded enthusiastically to new fashions. Bright colors like hot pink and citrus and new career lines from Tommy Hilfiger and Calvin Klein, aimed at department stores, helped draw shoppers.
Federated Department Stores Inc., citing strong sales in career apparel and accessories, reported a 6.8 percent gain in both same-store and total sales. Analysts expected a 5.8 percent increase.
Penney said same-store sales in its department stores rose 11.4 percent. Analysts expected a 7.3 percent gain. Total sales were up 10.8 percent.
Nordstrom posted a 15.9 percent gain in same-store sales, well exceeding the 8.1 percent expected by analysts. Total sales increased 19.8 percent.
AnnTaylor Stores Corp. recorded a 12 percent increase in same-store sales, compared to analysts' 7.4 percent forecast. Total sales were up 23.6 percent.
Limited reported same-store sales were up 15 percent, beating analysts' estimates of an 11.2 percent increase. Total sales rose 13 percent.
Chico's FAS Inc. reported an 18.9 percent same-store gain, compared to analysts' 12.6 percent projection. Total sales were up 50.8 percent.
On Wednesday, teen retailer Hot Topic, Inc., reported a 3.9 percent rise in same-store sales for March. Analysts expected 5.3 percent. Total sales were up 28 percent.
And American Eagle Outfitters, Inc., said same-store sales rose 7.6 percent, a bit below the 7.8 percent analysts expected. Total sales rose 17.6 percent.