It’s seriously time to get your holiday shopping done

(CNN) 鈥� Last-minute holiday shoppers may want to give their digital carts a hard look.

With colder temperatures potentially delaying shipping, carriers being overwhelmed with orders and some items simply out of stock, there are plenty of risks for procrastinating shoppers. More than half of Americans are worried about deliveries being delayed this holiday season, according to a study in October by .

Extreme weather could create delays for parts of the country. 鈥�(For) last-minute shopping, there鈥檚 going to be some issues,鈥� said Tyler Roys, senior meteorologist at Accuweather, who noted either snow or rain for most regions.

It doesn鈥檛 help matters that Amazon workers are on strike on the final weekend before Christmas. Amazon says customers can expect their packages to arrive on time, but logistics experts warn some shipments could face minor delays with since Thursday in California, Georgia, Illinois and New York.

A spokesperson for Amazon told CNN it disputes the reported number of striking workers and said the people picketing outside its facilities are 鈥渁lmost entirely outsiders.鈥� Amazon also said its operations have not been impacted.

Most of Amazon鈥檚 customers won鈥檛 be affected because the company has a high number of facilities, said Satish Jindel, president of ShipMatrix, a software provider that tracks delivery data for package shippers.

鈥淭hey will have the ability to ship product from other locations. They won鈥檛 be shut down,鈥� he said. 鈥淪ome packages that might have taken one day to be delivered will now take two. Some that might have taken two days will take three. But it won鈥檛 be that many.鈥�

Amazon customers may notice that some items will have an 鈥淎rrives before Christmas鈥� message posted to their order.

Amazon said in October that it would hire 250,000 transportation and warehouse workers for the volume of shipping this season as was expected to increase by as much as 3.5% from last year 鈥� a total of $989 billion.

As of early December, though, only 10% of consumers reported they were completely done shopping, according to the National Retail Federation. Between the Saturday before Christmas and December 25, about 157.2 million shoppers were , the NRF estimated.

鈥淲hether shoppers have planned out their shopping list or are waiting until the last minute, most shoppers still have purchases left to make before December 25,鈥� said Phil Rist, executive vice president of strategy at Prosper Insights & Analytics, which conducted the NRF December holiday consumer survey.

The shorter window between Thanksgiving and Christmas this year could play a role in last-minute shopping. With five fewer days than usual between the two holidays, the NRF estimated the Saturday before Christmas would have more buyers heading to stores and snagging deals online than last year.

More shoppers plan to finish their shopping online (49%) than department stores (37%), discount stores (27%), or clothing and accessory stores (25%), according to the NRF.

CNN鈥檚 Chris Isidore and Erika Tulfo contributed to this report.

The-CNN-Wire