Retail expert Kniffen: 2016 will be tough for these

What's ailing retailers?

Brick-and-mortar retailers will face more pain in 2016 as online retailers gain more ground, retail analyst Jan Rogers Kniffen said Wednesday.

"The penetration of online is going to be higher and the penetration of off-price is going to be higher, so it's still going to be a difficult year for brick-and-mortar retailers," the CEO of J. Rogers Kniffen WWE told CNBC's "Squawk Box."

Unseasonably warm weather, among other factors, has weighed on sales at brick-and-mortar retailers this fall and winter, as well as on their stock prices.

"The average temperature has been 20 degrees above normal. I left my coat in the car. Did anybody wear a coat this morning? No," Kniffen said. "That is hurting sales. It's causing inventories to be too high. There's lots of issues selling outerwear."

Pedestrians carry shopping bags on Black Friday through Herald Square in New York.
Can last-minute shoppers save the holiday season?
Holiday shoppers at a Macy's store in New York.
Trading retail: Brick-and-mortar names to watch

Macy's has seen its shares tumble 45 percent in 2015. In contrast, is one of the best-performing stocks within the S&P 500 this year, gaining more than 110 percent.

Macy's (Blue) versus Amazon (Green) YTD (%)

Source: FactSet

"We're moving to the point where 'omnichannel retailing' is no longer going to be called 'omnichannel retailing,'" Kniffen said. "Things that aren't omnichannel retailing are going to be the oddballs."