Did you know that your nose protects you from germs? The nose makes small sacs called extracellular vesicles. These sacs prevent bacteria from causing infections. In this study, we investigated how the nose uses extracellular vesicles to fight viruses. We hypothesized that cold weather decreases the nose’s ability to prevent viruses from infecting cells. Our findings confirmed that the nose does make extracellular vesicles when exposed to a virus. They contain molecules that attach to and kill the viruses. But the amount of extracellular vesicles decreases in colder weather. Furthermore, when it’s cold, the extracellular vesicles do not contain as many molecules that can kill the virus. That means that we are more likely to get sick when it is chilly outside!