Winter is officially here, and people across the United States can attest to it: The temperature in Bismarck, North Dakota, marks 28 degrees today; Plattsburgh, New York, residents are freezing at 22 degrees; and large swaths of the Midwest report windchills in the upper teens.

If that's enough to keep you from wanting to step outside and go for a run to burn away those Christmas calories, you may want to ask Santa for some ColdGear clothing from Under Armour. The sports clothing and accessories company has developed that line specifically for athletes who need to perform under adverse weather conditions.

ColdGear's "soft, thermo-conductive coating inside absorbs and retains your own body heat," the company says, and does not just make you warm but helps keep you warm. Many joggers and other athletes across the country, meanwhile, have found that to be true.

Cleveland runner Greg Strosaker, who writes the Predawn Runner blog, says he tested some of the ColdGear products after his wife got them for him for Christmas last year.

"I don't know what impression you hold of Under Armour, but mine is that they excel at, well, base layers," Strosaker notes. "And ColdGear absolutely fits that image."

The runner tried the Fitted Mock Long Sleeve Technical Top and says it performed to his expectations.

"The company claims that ColdGear 'is the only layer you need,'" Strosaker reports. "While I was a bit skeptical of the claim, it is immediately obvious for the shirt that this is a warm piece of apparel, and any notions you may have about the layers needed at a given temperature need adjusted."

Strosaker found that an additional layer, such as a vest, may be comfortable in temperatures from 5 degrees up to the low 20s.

"It would be fine on its own above (approximately) 25 degrees," he says.

Skiing teacher and ski journalist Robert Stewart reports similar positive experiences on his blog, Snow.Guide.

"I'm very pleased with my Under Amour ColdGear mock, and it's a great addition to my various thermal base layer garments," Stewart says. "(But) I'm not looking forward to the temperatures dropping to below -10 (degrees) again!"

The whole product line of ColdGear products is available on Under Armour's website.