CHICAGO — It may not be sweater weather yet, but the annual deluge of pumpkin-flavored treats is on its way.

Pumpkin-spice lattes will go on sale at McDonald’s restaurants in some regions starting Sept. 1 and at Starbucks cafes the following day. Starbucks is letting customers get the drink early this year by whispering a code — “First PSL” — to a cafe barista.

American’s craving for pumpkin delicacies has become a seasonal ritual that’s only grown in recent years. The success of the Starbucks lattes, which the chain started selling about a decade ago, has prompted a flood of pumpkin-flavored fare, including Pinnacle brand pumpkin-pie vodka from Beam Suntory and pumpkin-spice Jell-O from Kraft Foods.

“Pumpkin itself is a comfort food,” said Bill Chidley, brand consultant at ChangeUp in Dayton, Ohio. “It’s just a perennial favorite, like turkey at Thanksgiving, eggnog at Christmas, fireworks on Fourth of July.”

U.S. pumpkin-flavored sales jumped 14 percent to about $308 million in 2013, according to Nielsen. The extra demand helped push pumpkin prices up 11 percent last year, the U.S. Department of Agriculture reported in March.

New and seasonal food offerings have become a key strategy Starbucks and other restaurants use to boost sales. McDonald’s began selling its pumpkin lattes last year, while Dunkin’ Donuts has added pumpkin flavors to muffins, doughnuts and coffees.

Seattle-based Starbucks, which has about 11,700 U.S. locations, said last year that it had sold more than 200 million pumpkin lattes since the introduction in 2003. The world’s biggest coffee-shop chain also is offering pumpkin scones, pumpkin cream-cheese muffins and Via pumpkin-spice instant latte drink mixes this year.

Other eateries are trying to compete with Starbucks’ pumpkin lattes with new items. Dunkin’ Donuts is rolling out pumpkin creme brulee coffee for this year, and Baskin-Robbins is introducing pumpkin-cheesecake flavored ice cream in September.

McDonald’s is selling its pumpkin lattes this year only in certain regions “where it’s right” for customers, including some locations in Atlanta and the Midwest, said Lisa McComb, a spokeswoman for the Oak Brook, Illinois-based company.

A small McCafe pumpkin latte costs $2.29, and diners can get it made with whole or nonfat milk. A small Starbucks pumpkin-spice latte with 2 percent milk and whipped cream has 300 calories and costs $3.95 to $4.15, depending on the market.

Packaged-food companies are getting in on the action too. PepsiCo’s Quaker brand will offer a pumpkin and spice flavored instant oatmeal for a limited time this fall, said Jay Cooney, a spokesman. General Mills will sell a half-dozen pumpkin-flavored products this season, including Betty Crocker cookie mix, Pillsbury cinnamon rolls and Yoplait yogurt.

Photos of Oreo Pumpkin Spice cookies have been popping up on Twitter and websites, with some people claiming to have tasted them. Mondelez International, the company behind the iconic Oreo sandwich cookies, declined to provide details of the new product.

Pumpkin isn’t just for humans anymore either. Purina said last month that it had introduced a salmon, egg and pumpkin blend of its Purina Beyond dry dog food.

Even if pumpkin risks overexposure, the trend shows no sign of going away, Chidley said.

“I don’t think it has an expiration date, not in the foreseeable future,” he said.