NEW YORK — Same-store sales rose modestly in September, with analysts blaming economic uncertainty linked to the then-looming government shutdown, and unusually warm weather that hurt sales of fall goods.

Same-store sales rose modestly in September, with analysts blaming economic uncertainty linked to the then-looming government shutdown, and unusually warm weather that hurt sales of fall goods.

A preliminary tally of nine retailers that still report monthly sales figures, put together by the International Council of Shopping Centers (ICSC), found that comparable-store sales in September were up 2.7% compared to the same period last year. That is down from the 3.5% increase posted in August.

Another estimate, by Retail Metrics Inc., put the same-store sales gain for retailers in September at just 2.3%. Analysts had predicted a 3.4% increase.

Costco Wholesale Corp. reported sales of $9.86 billion for the five weeks ended October 6, up 6% from the year-ago period. Same-store sales, excluding the negative impact of gasoline deflation and foreign exchange, ­advanced 5%.

Walgreen Co. had September sales of $5.92 billion, up 8% from last year, with same-store sales climbing 7.4%. Total front-end sales increased 4.1% , while comparable-store front-end sales increased 2.9%. Customer traffic in comparable stores decreased 0.8% while basket size increased 3.7%. September pharmacy sales increased by 10.4%, while comparable-store pharmacy sales increased 10.2%, and increased by a calendar day-shift adjusted 7.3%.

Rite Aid Corp.’s same-store sales increased 1.9%. September front-end same store sales decreased 0.5%, while pharmacy same-store sales, which included a negative impact of about 100 basis points from new generic introductions, increased 3.1%.

Fred’s Inc.’s same-store sales increased 2.8% in contrast to a decline of 3.8% in the same period last year. Total sales rose 4% to $177.3 million.

"We continue to experience success from our reconfiguration plan," said chief executive officer Bruce Efird, noting the same-store sales gain was at the high end of management’s projected range.

For October, ICSC research anticipates that comparable-store sales will increase between 3% and 4%. However, the federal government stalemate had the potential to curb spending.