GREENWOOD, Miss. (AP) _ Mississippi Delta cotton farmers are stepping out from their first profitable year since 1982, thanks to favorable weather and steady demand from the textile industry.

But weather can't be controlled and cotton's popularity in the international fashion industry is declining, analysts say.

''Last year, we had a couple of plants running 100 percent cotton. That isn't the case now,'' said Larry Martin of Alice Manufacturing, one of South Carolina's largest privately held textile companies.

''Last year was one of those once-in-a-100-years things,'' Mississippi Extension Service analyst O.A. Cleveland said.

Fighting a trend that could slice into their spouses' livelihood, a group called Cotton Wives is trying to make sure cotton never goes out of style. The women, married to cotton farmers, put on all-cotton fashion shows in the South, promoting the fruits of their husbands' labor.

In 1987, Mississippi produced 1.75 million bales of cotton, up from less than 1.2 million in 1986, extension economist Bob Williams said. The yield per acre in 1987 was 832 pounds, second only to the 1982 record of 853 pounds per acre. In 1986, production reached an all-time low of 571 pounds per acre, Williams said.

Last year's selling price averaged 65 cents a pound. But now 1987 crops are selling for a cash price of 59 cents and 1988 crops are pre-selling for 57 cents, Cleveland said.

America is about 18 months behind Europe in fashion, and 16 months ago cotton began to fade from European clothes, meaning farmers can no longer rely on the textile market as a major purchaser, Cleveland said.

''The market is telling us that cotton demand will not be as strong in 1988,'' he said. ''Nothing that good lasts forever.''

Alice's five plants in South Carolina are running more cotton blends than they have in the past, said Martin.

''There has been some change in the amount of 100 percent cotton we are producing. It's predicated on demands and conditions in the marketplace,'' he said.

Store buyers agree that there has been a drop-off in the demand for cotton, but say Southerners will never abandon their preference for the fabric which helps them keep cool.

''The 100 percent cotton has not been in as big demand across the country. But the South loves its cotton,'' said Jan Collins, sportswear buyer for the Sunbelt's McRae's Department Stores.

The rest of America may be riding on European coattails, but the South tends to do its own thing, said Kathryn Becker, buyer for the Jackson clothing store High Cotton.

''That trend is usually in the fashion industry as a whole,'' Becker said. ''The South doesn't usually home in on that kind of thing.'' But some buyers say rayon and polyester are making a comeback as women seek a softer, more feminine look that cannot always be achieved with cotton.

''The softer rayons are selling big, which may be taking away from the cotton business,'' said Shelia Walters, a sportswear buyer for New Orleans- based D.H. Holmes Department Stores.

But buyers say don't write cotton off as a washed-up fabric.

''Cotton is a very important project to us almost year-round,'' McRae's fashion director Pat Priebe said. ''Our buyers do not have trouble getting it and we don't have trouble selling it.''

Cotton Wives, who say the trend in Europe doesn't dictate American fashion and certainly doesn't amount to a hill of beans in the South, market their crops through schools, public appearances and style shows.

''We go to schools and tell them to check labels, make sure they're 100 percent cotton and made in the U.S.A.,'' says cotton wife Janie Braswell of Morgan City. ''We push cotton by telling them they're helping out the farmers.''