Smoothies Are Top Banana in Any Weather

But die-hard smoothie fans will continue to buy the beverage in freezing weather, says Folkman. He sold the Fruithy -- the company's smoothie drink -- and other Frutation delicacies during a recent 15-degree cold snap.

Minnesota, known for its harsh winters, happens to be one of Maui Wowi's biggest markets, says COO Mike Edwards. "We're a tropical escape there," he says. The franchise has also added Hawaiian coffees and snack foods to its menu.

Maui Wowi, franchising since 1997, is selling about 100 franchises per year -- a figure that's likely to remain steady, says Edwards.

Weather is irrelevant to sales of BoosterJuice, because the product is intended as a meal replacement, says U.S. chief executive Jon Amack. With 25 grams of protein per smoothie, "It's not just a drink to enjoy when it's sunny out and you're rollerblading," he says.

Kahala-Cold Stone Corp., a holding company for 13 fast-food brands is avoiding the weather issue entirely by opening a new smoothie-franchise concept, NRGize Lifestyle Café, in health clubs, where it's likely to find a captive audience of sweaty, parched patrons. The company recently signed an agreement to become the exclusive food and beverage provider for health club giant L.A. Fitness.