I guess the CDC updated their page.

https://www.cdc.gov/ncird/whats-new/covid-19-can-surge-throughout-the-year.html

Many respiratory virus illnesses peak during the winter due to environmental conditions and human behaviors. COVID-19 has peaks in the winter and also at other times of the year, including the summer, driven by new variants and decreasing immunity from previous infections and vaccinations. You can protect yourself from serious illness by staying up to date with vaccinations, getting treated if you have medical conditions that make you more likely to get very sick from COVID-19, and using other strategies outlined in CDC's respiratory virus guidance.