Chris Woodyard

USA TODAY

With the big shopping season just getting started, one of the most closely watched forecasts for holiday sales is predicting a merry time ahead for traditional retailers — and an even merrier one for online sellers.

The National Retail Federation predicted Tuesday that sales will tick up 3.6% overall in November and December to $655.8 billion. That would make it far better than the 2.5% average growth over the 10-year period, or even the 3.4% average in the last seven years as the nation emerged from recession. The forecast focuses on retail sales, excluding spending on cars, gasoline and restaurants.

The bigger gainers would be online sellers. Non-store sales are going to increase from 7% to 10%, the NRF forecasts, to $117 billion.

“All of the fundamentals are in a good place, giving strength to consumers and leading us to believe that this will be a very positive holiday season,” NRF CEO Matthew Shay said in a statement. “Our forecast reflects the very realistic steady momentum of the economy and industry expectations.”

Other shopping outlooks are also rosy, predicting double-digit online sales growth.

In August, Kantar Retail predicted a holiday-season uptick of 3.8%, up from 3.4% last year, using the same basis as the NRF. Of that, conventional stores would see a 2% gain while online retailers will see a 16% increase, the most since 2011. A big factor in the jump is that lower food and gasoline prices will put more cash in shoppers' pockets.

And eMarketer, which keeps tabs on online sellers, said digital sales will rise by 17.2% in November and December, and that total holiday sales will top 10% for the first time.

In making its prediction, the NRF cited the general health of the U.S. economy — one in which more consumers are likely to whip out credit cards for gifts.

"Consumers have seen steady job and income gains throughout the year, resulting in continued confidence and the greater use of credit, which bodes well for more spending throughout the holiday season,” NRF Chief Economist Jack Kleinhenz said in a statement.

The season will also provide temporary employment for 640,000 to 690,000 workers, the NRF says.

Still, there's plenty that could go wrong, the NRF acknowledges. The forecast could be thrown off by a global crisis, fallout from a contentious presidential election and a winter-season heat wave that could have people wanting to play in the sunshine instead of cooping themselves up inside warm malls.

But for now, the federation says it is staying positive, expecting shoppers to return to their die-hard hit-the-mall ways.

"Economic spending power of the consumer is resilient and it should never be underestimated,” Kleinhenz says.