The nation's major retailers said yesterday they had sluggish sales in October, when unseasonably warm weather discouraged shoppers from buying winter clothes and high interest rates kept down demand for big-ticket goods.

"The numbers are pretty disappointing across the board," said Walter F. Loeb, a retail analyst with the investment firm of Morgan Stanley & Co.

Monroe H. Greenstein, an industry analyst with Bear, Stearns & Co., said: "Sales were poor. Particularly poor were durable goods sales."

Sears, Roebuck & Co., the nation's biggest retailer, said its sales edged up 2.1 percent from the same month in 1983. K mart Corp., the No. 2 chain, reported a 17.8 percent jump, but it has opened more stores since last October.

J. C. Penney Co., ranked third, posted an 8.6 percent gain; No. 4 Federated Department Stores Inc. had a 9.4 percent increase, and Dayton Hudson Corp., ranked fifth, was up 14.4 percent.

"The most obvious factor is that weather has been extremely warm around the country with the exception of the Mountain states," Greenstein said.

Loeb said, "People didn't buy the overcoats or winter clothes or any heating equipment."

Jeffrey Feiner, an analyst with Merrill Lynch, Pierce, Fenner & Smith Inc., said poor sales of durable goods affected Sears' results, in particular.

He blamed weak sales of items expected to last three years or more on high interest rates on consumer loans and on the fact that pent-up demand for durable goods was met in the preceding 25 to 26 months.

The sluggish sales have forced retailers to "maintain extremely aggressive pricing strategies," Feiner said. As a result, retailers' third-quarter earnings reports will be disappointing industrywide, he predicted.

Sears, based in Chicago, said its October sales totaled $1.82 billion, compared with $1.78 billion a year ago. So far this fiscal year, which began in February, sales have risen 6.1 percent to $16.5 billion from $15.5 billion.

K mart, of Troy, Mich., said its sales for the month rose to $1.54 billion from $1.3 billion. For the 39 weeks, sales are up 9.8 percent, from $12.95 billion to $14.2 billion.

Penney, based in New York, said its sales were $908 million in October, compared with $836 million for the same period in 1983. So far this year, sales have risen 15.1 percent, to $8.2 billion from $7.1 billion.

Federated said its four-week sales rose 9.5 percent to $733 million, from $670 million last October. Year-to-date sales are up 11.5 percent to $6.4 billion from $5.7 billion. The company is based in Cincinnati.

Dayton Hudson, of Minneapolis, said its sales for the month came to $571 million, compared with $499 million last October. Sales for the nine months jumped 16 percent to $4.99 billion from $4.3 billion.

Here are the results of the remaining retailers who make up the nation's top 10: Montgomery Ward had a 12.1 percent improvement in October. The Chicago-based subsidiary of Mobil Corp. said sales totaled $521 million, compared with $465 million in October 1983. Sales for the 39 weeks rose to $4.5 billion from $4.1 billion, a 10.7 percent gain. F. W. Woolworth Co., based in New York, said the month's sales rose 2.7 percent to $411 million from $401 million last October. For the nine months, sales increased 5.4 percent to $3.9 billion from $3.7 billion. Wal-Mart Stores Inc. said its sales increased 30 percent, but it has opened 104 stores since last October. October sales totaled $550 million compared with $422 million last year. Year-to-date sales are up 39 percent, to $4.3 billion from $3.1 billion. The retailer is based in Bentonville, Ark. May Department Stores Co. of St. Louis said four-week sales rose 10.7 percent to $352 million from $318 million last October. Sales for the first nine months totaled $3.12 billion, a 13.7 percent gain over $2.75 billion last year. R. H. Macy & Co. had a 4.4 percent increase for the month. Based in New York, Macy's said its four-week sales came to $317 million, compared with $304 million a year ago. Nine-month sales rose 12.7 percent, to $2.84 billion from $2.52 billion.