(NEXSTAR) — If you cut it close by sending out Christmas gifts at the last minute this year, your presents may not arrive in time thanks to a bitterly cold storm system that has blasted key package distribution hubs.

UPS and FedEx each issued alerts in the last 24 hours letting customers know that the storm has forced the companies to prioritize crew safety over speed.

“Potential delays are possible for package deliveries across the U.S. with a delivery commitment of Friday, December 23 and Saturday, December 24. FedEx is committed to provide service to the best of our ability,” the company stated on its website Friday morning.

FedEx said distribution hubs in Memphis and Indianapolis were hit particularly hard by the storms, meaning packages passing through those locations are most at risk of delay. The same is true at UPS hubs in the area.

“Significant weather events across several regions of the U.S. are impacting the UPS Air and Ground network, including UPS hubs in Louisville, Kentucky and Rockford, Illinois. As a result, some delivery and pickup services in these areas will be affected,” UPS posted on its website Thursday night.

Both courier networks urge customers to track their packages online for updated delivery information. Storm disruptions were not limited to package delivery.

More than 200 million people were under some form of winter weather advisory or warning on Friday, the National Weather Service said. The weather service’s map “depicts one of the greatest extents of winter weather warnings and advisories ever,” forecasters said in a statement Friday.

More than 3,400 flights within, into or out of the U.S. were canceled Friday, according to the tracking site FlightAware, causing more mayhem as travelers try to make it home for the holidays. More than 458,000 homes and businesses were without power Friday morning.

The Associated Press contributed to this report.