Some people went to bed irate on Christmas Eve, furious that FedEx did not deliver their packages in time for the holiday.

Severe weather in the Southeast delayed shipments for some customers who were expecting to be able to place their gifts under the tree Thursday night. FedEx's main hub in Memphis, Tennessee, was affected by the heavy rain and wind.

To make up for the delays, FedEx (FDX) said some of its employees have volunteered to work on Christmas to deliver delayed packages to customers.

"FedEx is doing everything possible to get customer shipments delivered by Christmas in spite of slight delays due to heavier than planned last-minute shipment volumes and severe weather outbreaks in some areas of the U.S.," FedEx spokeswoman Rae Lyn Rushing said in a statement.

The delivery company said priority is being given to residential shipments on Friday. FedEx will also try to get packages to customers who were not at home to accept deliveries on Thursday.

FedEx Express stores will be open from 9 a.m. to 1 p.m. on Christmas so that customers can pick up their packages.

Anger toward FedEx bubbled over on social media Thursday night and Friday morning, as people blamed the delivery company for ruining their holiday. Many people called FedEx the "Christmas Grinch."

Some UPS (UPS) packages were delayed as well, though FedEx's rival seemed to be less impacted by the storms.

"There may be some individuals who had some delayed packages, but overall, most people got the packages they were promised," said Peggy Gardner, spokeswoman for UPS, in an email. "There hasn't been a big issue with packages not being delivered."

Social media was much kinder to UPS than FedEx.

The shipment delays echo 2013, when both UPS and FedEx were unable to deliver many packages for Christmas due to similarly severe winter weather.

Both shipping companies got off to a bad start this holiday season, as they failed to keep up with a surge of last-minute online orders two weeks ago. But UPS and FedEx seemed to have righted the ship over the past week -- at least, until Thursday.

-- CNN's Chandler Friedman contributed to this report