Shoppers will spend $112 billion online in November and December, a jump of 13% from the $99 billion spent in the same period in 2015, according to market research firm Forrester.

So why are sales expected to jump this season? Forrester said that a stable economy could be a factor, which has already helped to lift e-commerce over the past nine months. Online retail sales from January through September grew 15.3% to $290 billion, which is a faster pace than the 14.7% growth to $251 billion in the same period last year.

Additionally, colder weather this season could help increase sales online, Forrester said. An expected cooler winter this year could help boost sales of items like winter jackets, boots, and other accessories and apparel. Last year, unseasonably warm weather in the Northwest U.S. contributed to lower-than-expected sales.

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Online retailers are already gearing up for the potentially record-setting holiday shopping season. Amazon (AMZN) launched its Black Friday deal store on Nov. 1, nearly a month before one of the largest U.S. national shopping days takes place the day after Thanksgiving.

Walmart (WMT) also said recently that it will offer more lower-priced items this year and that those discounts will be available for an indefinite period.

Still, online spending still represents only a small portion of overall holiday spending. It is expected to account for 16% of sales during the holidays, up from 12% outside of the holiday season.