Every winter, influenza shows up in a familiar way: schools and workplaces see more absences, urgent care wait times climb, and many households cycle through coughs, fevers, and fatigue. That’s because flu season in the U.S. typically ramps up in fall and winter, with flu activity most often peaking between December and February — and historically, February is the most common peak month.

That timing matters. When we hit the “peak,” flu spreads more easily, more people are contagious at the same time, and the chance of bringing illness into your home, workplace, or social circle goes up. The good news: a few practical habits—done consistently—can make a real difference.

As of early January 2026, CDC survey data show that 44.1% of adults received a flu shot this season. That means more than half of adults are still unvaccinated during the heart of flu season.