It happens every year around this time.
The weather gets colder and cold and flu viruses start making the rounds. But this year, there's a third illness expected to enter the mix: COVID-19.
New cases are coming in at a record pace. Hospitalizations and deaths are rising, too.
Now, public health experts say the pandemic is in a "critical phase,” warning winter could be the worst season yet for the novel coronavirus.
Cold weather is one of the main reasons that doctors expect cases to rise sharply over the next couple of months. Researchers say the virus survives best in cold, dry conditions without direct sunlight. The same conditions that fuel cold and flu seasons.
The cold weather also pushes more people to spend time indoors, where the virus can spread more easily, especially if air ventilation is poor.
“Pandemic fatigue" is another reason COVID-19 cases could surge this winter. The surgeon general says people aren't taking precautions as seriously as they were before and that it's already causing an increase.
That fatigue is expected to get worse this holiday season. Many people got together for Thanksgiving, and Hanukkah, Christmas and Kwanzaa are right around the corner.
Experts say while some people are simply tired of social distancing and being isolated, others plan to make an exception for just one day with family.
Aside from warm weather, experts think this spring will bring a brighter outlook for ending the pandemic, with new therapeutics and vaccines to help bring cases under control.