No matter what your grandmother may have said, going outside in the winter hatless does not increase your risk of flu. While there might seem to be a connection -- since flu season coincides with colder months in the U.S. -- there isn’t. After all, flu season is the same throughout the whole country: even if it’s frigid in Minnesota, it’s still warm in Florida. The rise and fall of flu season each year has more to do with the natural cycle of the virus, although experts aren’t exactly sure how it works.

Colder weather might increase the risk of flu in one way: We might come into closer contact with other people because we’re all stuck inside. That could make it easier for the virus to spread.