U.S. health experts on Thursday warned Americans that a rising tide of COVID-19 cases led by the Omicron variant threatens major disruptions to their lives, from schools to shopping, and urged them to prepare now for a challenging month ahead.

For the second day in a row, the United States had a record number of new cases based on the seven-day average, with more than 290,000 new infections reported each day, a Reuters tally showed.

At least 18 states and Puerto Rico have set pandemic records for new cases, according to the tally. Maryland, Ohio and Washington, DC, also saw record hospitalizations as overall U.S. COVID hospitalizations rose 27%.

The surge comes amid increased holiday travel, with New Year's celebrations still to come, and as schools grapple with students' return to classrooms following winter breaks.

"We are going to see the number of cases in this country rise so dramatically, we are going to have a hard time keeping everyday life operating," Dr. Michael Osterholm, an infectious disease expert at the University of Minnesota, told MSNBC.

"The next month is going to be a viral blizzard," he said. "All of society is going to be pressured by this."