Retailers could be seeing a little more green from this year's holiday season.

Retail sales in November and December could hit $617 billion, according to National Retail Federation projections released today. That's a 4% increase over 2013, which had seen a meager a 3% increase over 2012 holiday sales.

"Retailers could see a welcome boost in holiday shopping, giving some companies the shot in the arm they need after a volatile first half of the year and an uneventful summer," said NRF President-CEO Matthew Shay in a statement.

Online sales, meanwhile, could grow as much as 11%, an acceleration from 2013's 8% increase, according to shop.org, a division of NRF.

The NRF said that an improving economy would drive the gains.

"In the grand scheme of things, consumers are in a much better place than they were this time last year, and the extra spending power could very well translate into solid holiday sales," said NRF Chief Economist Jack Kleinhenz in a statement.

The sales-total figures do not include cars, gas and restaurants.

Other forecasters predicted sales growth as well. Deloitte said the increase could reach 4.5%. The consulting firm called the growth "modest" but added that retailers would see a whopping 14% increase in online and mail order sales.

It also predicted "digital interactions will influence 50 percent" of in-store purchases, with customers looking up products before or during shopping.

In-store pickup opportunities -- which is available at retailers as varied as Kmart, Best Buy and Nordstorm -- will also help attract customers, according to Blueocean Market Intelligence, an analytics firm.

With expectations high for a happier holiday season, marketers are sure to rev their marketing engines in the coming weeks. Already, Kmart -- no stranger to Christmas Creep -- launched an ad titled "Merry Birthday" last month. Last year, the retailer raised the ire of some by launching its first Christmas ad 105 days before the actual holiday.

The new ad takes a humorous approach to Christmas Creep, with a Kmart employee announcing, "Hello America, It's too early for Christmas. So just to be clear, this is not a Christmas commercial. However, let's say you have an event in late December that you need a lot of gifts for, like maybe your entire family is having a birthday on the same day. Now is the time to go to Kmart and put those gifts on layaway."

Kmart's emphasis on lay-away continues one key trend from the last few years as consumers seek value. According to the NRF, despite being ready to put down more than they did last year, shoppers this year will still be price-conscious.

Walmart, too, has recently begun airing lay-away ads, but those don't have an obvious holiday hook.