Students making preparations to return to Cambridge after a week of extended relaxation and relatively warm weather found their plans thwarted this weekend by an unexpected snowstorm that struck the United States Midwest and Plains regions, depositing more than 10 inches of snow in some states and delaying flights across the country.

National Weather Service reports indicate that parts of Colorado and northwest Kansas were blanketed in approximately 10 to 15 inches of snow within hours of the storm’s arrival around midnight on Saturday. Southwestern Nebraska was also heavily affected, and the storm dumped seven to nine inches from eastern Kansas into central Missouri before moving on to St. Louis, western Illinois, and Ohio on Sunday. Forecasters expected the storm system to deposit eight to 10 inches in St. Louis, six to 10 in Illinois, and five to nine in Ohio by Sunday night.

Storm-related accidents, poor visibility and other dangerous weather conditions forced the closure of many roads and highways, including the I-70 from Denver to Colby, Kansas.

In addition, 442 flights were canceled and 6,579 were delayed nationwide as of 9 p.m. on Sunday, according to flightstats.com. Seven of the canceled and 113 of the delayed flights were scheduled to land at Logan International Airport in Boston.

With the numerous cancellations and delays, many Harvard students were forced to modify their plans for arrival on campus before the start of classes.

“Both of my roommates are on a flight back right now,” said Amy Z. Chen ’14 at 10 p.m. on Sunday. Chen’s roommate Kristin I. Barclay ’14 experienced at least three hours of continuous delays before boarding a flight from Minneapolis to Boston on Sunday night, according to Chen.

Forrest S. Brown ’15, who returned to campus from the St. Louis area on Sunday, reached Boston 12 hours after his original arrival time.

“While I’m devastated to [have missed] Sunday night brain break, I’m more worried about the increasing frequency of extreme and off-season weather events,” he said.

The storm may have altered many travel plans, but it did not change the NCAA men’s basketball tournament schedule. The University of Kansas Jayhawks defeated the University of North Carolina Tar Heels in a 70-58 victory in Kansas City, Mo., on Saturday.

The storm is expected to weaken as it travels eastward late Sunday night, with predicted total snow accumulation in Pennsylvania between three and eight inches. Before it departs off the coast of New Jersey on Monday night, the system could drop one to three inches in southern New York and New Jersey.