Online holiday retail sales will reach $89 billion this year, according to Forrester’s 2014 Online Holiday Retail Forecast, representing 13% growth for the months of November and December over the same time period in 2013. This will equate to $10 billion more in sales over the next two months compared with last year. Further, Forrester expects this figure to represent 14% of total retail spend during the holiday season.

This season marks strong opportunity for retailers to acquire new customers, as web users are more likely to try eCommerce for the first time now more than any other time of year. Forrester predicts 3.4 million customers will fall into the “new shopper” bucket this holiday season.

Of course, there are still a number of challenges that could prove problematic for online retailers over this crucial sales period, writes Vice President and Principal Analyst Sucharita Mulpuru in a new blog post.

All eyes will be watching the carrier networks for delayed deliveries after last year’s notable issues. Forrester estimates that there are nearly seven times as many eCommerce packages shipped daily in the two weeks before Christmas as there are packages shipped daily between the months of January and October. In fact, according to Mulpuru, retailers that have late bursts in holiday demand are likely to have many late shipments and disappointed shoppers. As such, she recommends retailers closely consider their contingency plans this year — with caveats on marketing messages, and more importantly, planning for a higher level of refunds and returns.

To learn more about 2014 US online holiday sales, visit the eBusiness & Channel Strategy blog.