FORGET the Great Pumpkin, Halloween, and Thanksgiving. In many major retail outlets around the United States, Christmas promotions are under way, or about to begin.At fashionable Lord & Taylor in the New York area, Christmas trim went up several weeks ago. At K mart Corporation in Troy, Mich., company officials are putting the wraps on a major holiday promotion that will begin in mid-November. At the Ames Department Store in Franklin, Mass., little Christmas lights twinkle in cadence with holiday melodies. Unfortunately, there's a Grinch in the retailer's holiday cheer: US consumers are not yet opening their wallets in any substantial way. "Consumer spending is in a cautious, frugal, and thrifty mode," says Kurt Barnard, who publishes Barnard's Retail Marketing Report, a monthly trade publication. "Retailers who offer moderately priced goods that are attractively packaged will do well," says Mr. Barnard, but retailers "who offer luxury items" or big-ticket durable goods such as refrigerators, are "going to find the going very tough." If retailers are concerned, they have good reason. Year-end holiday sales are increasingly important to merchants, representing the biggest overall sales period. And this year there are some six fewer Christmas-shopping days after Thanksgiving than last year. During much of the 1980s, says Barnard, annual gains by retailers were steady - with a significant part of that growth occurring at the end of the shopping year. But "beginning in late 1987 and early 1988, we witnessed the start of a consumer spending retrenchment." The spending cutback is not just linked to recession; it is also related to changing demographic patterns, Barnard says, as the population ages. Older consumers tend to be more cautious about financial outlays. Moreover, as the baby-boomers of the 1980s settle down to raise families, "they find that they have less disposable income," since so much of their salary goes to meeting family needs. "Traditionally, consumers tend to do a lot of buying after the end of a recession," says Stephen Gallagher, an analyst with Kidder, Peabody & Co., Inc., an investment house. "This time that doesn't appear to be the case. I'd look for retail spending to be slightly better than flat [in the weeks ahead]. But it's not going to be stellar." Buyer confidence remains low. "Consumer evaluations of their own personal financial situations is close to a record low," says Richard Curtin, director of a survey program about US consumers, at the University of Michigan at Ann Arbor. "Retailers and consumers are now eye-balling each other," says Mr. Curtin. Consumers are waiting for the type of deep price discounting that occurred last Christmas. Retailers, who have kept their inventories far lower than was the case in 1990, have been holding off on price cuts. But eventually, says Curtin, a few retailers will probably opt for discounting, which might bring out shoppers. Inventory reduction has been fairly extensive, much of it related to better utilization of computer technology. Toys * Us, the nation's largest toy chain, has reduced its store-wide inventory levels by about 15 percent, according to a recent report by Donaldson, Lufkin & Jenrette, an investment house. Unfortunately, many consumers just don't have "a great deal of extra income to spend on shopping," says Cynthia Latta, an economist with DRI/McGraw Hill, an economic consulting firm in Lexington, Mass. Income growth remains minuscule to nonexistent. In many families, someone has lost a job or is working reduced hours, and there is little likelihood of major expansion on the job front in the months ahead. On Oct. 29 the Commerce Department reported the economy expanded at an annual rate of 2.4 percent for the third quarter. DRI/McGraw Hill sees the economy growing modestly in the fourth quarter, at about 2.5 percent, although it could be as low as 2 percent. It projects growth next year at around 3 percent. The weather will play a major part in determining the extent to which consumers open their wallets. If temperatures are very cold, Ms. Latta notes, consumers will have to spend money on sweaters, woolen clothes, heating oil, etc. But if the weather is relatively warm - which has been the pattern in many parts of the US recently, that would work against consumer spending. Most needed to get consumers to spend are further declines in interest rates and steady growth in employment, says David Hale, chief economist with Kemper Securities Group Inc., an investment house in Chicago. He foresees additional reductions in interest rates by the Federal Reserve Board. But if the rate reduction proves ineffective in revving up the economy, a tax cut of some type will be seriously considered by the White House and Congress early next year, he adds.