"Flu season" is an interesting term.

The virus is around all year.
people only get sick in the winter months?

why? is it colder and the virus replicates better? Perhaps.
But the average temperature in February in Florida is +16 and Illinois is -7
Yet they are moth high risk based on the map.

Fact is in the winter people eat less healthy, see less sunlight and are less physically active.
As long as you work on improving your immune system you will be protected.