Covid-19 cases are climbing in places like the upper Midwest, Southwest and parts of the Northeast, hindering the nation’s progress in ending a surge triggered by the highly contagious Delta variant of the coronavirus. Nationally, the seven-day average of new cases appears to be edging back up after hovering just above 70,000 for several weeks, according to data from Johns Hopkins University, halting what had been a decline from the Delta-fueled peak that began in September. While the Southeast cools off from its summer surge, other regions are under pressure, including places where colder weather has brought people back indoors where the virus can more easily spread.

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