The National Retail Federation expects sales in the months of November and December to increase 3.9 percent to $602.1 billion, which would be a .4 percent increase from 2012’s 3.5 percent holiday season sales growth.

“Our forecast is a realistic look at where we are right now in this economy–balancing continued uncertainty in Washington and an economy that has been teetering on incremental growth for years,” says Matthew Shay, president and chief executive, the NRF. “Overall, retailers are optimistic for the 2013 holiday season, hoping political debates over government spending and the debt ceiling do not erase any economic progress we’ve already made.”

Economic variables including positive growth in the U.S. housing market and increased consumer appetite to buy larger-ticket items give retailers reason to be cautiously optimistic for solid holiday season gains.

According to the NRF, the holiday season can account for anywhere from 20-40 percent of a retailer’s annual sales, and accounts for approximately 20 percent of total industry annual sales. 

NRF’s holiday sales forecast is based on several indicators including consumer confidence, consumer credit, disposable personal income and previous monthly retail sales releases. It also includes the non-store category (direct-to-consumer, kiosks and online sales.)

In conjunction with the NRF report, Shop.org also released its 2013 online holiday sales forecast, which predicts that November and December sales will grow between 13 to 15 percent over last holiday season to as much as $82 billion.

“Online and mobile continue to be a leading area of growth for retailers. In this economy, savvy, cost-conscious consumers go to the web to do their research and get the best bang for their buck,” says Shay. “In addition to researching what their peers are saying online about products and gifts this holiday season, consumers will use the buy online/pick-up in store option, retailers’ apps and mobile websites to find something special for their loved ones.”