Parcel and trucking company UPS has offered a glimpse of its fourth quarter and 2013 earnings ahead of releasing its full report on Jan. 30.

It anticipates fourth quarter 2013 diluted earnings per share of $1.25, less than many earlier analyst estimates.

Full-year 2013 adjusted diluted earnings per share are expected to be $4.57, below the previously provided guidance of $4.65 to $4.85.

“U.S. results were negatively impacted by the challenges of the compressed peak season coupled with an unprecedented level of online shopping that included a surge of last-minute orders,” the company said. “In an effort to maintain service standards and commitments, UPS took extraordinary measures deploying additional equipment and people. For example, the company utilized 85,000 temporary employees, 30,000 more than planned. Also, weather events in December weighed on results.”

On Dec. 23, UPS said it delivered more than 31 million packages, the most ever and 13% over the prior-year peak day. This year's highest delivery day occurred six days later than expected and was 7.5% greater than planned.

“Despite fourth quarter performance, the company is confident of its 2014 outlook,” it said. “UPS expects full-year 2014 diluted earnings per share to grow in line with its long term targets of 10% to 15%, compared to 2013 adjusted results.”