does cold air kill fleas?

Answer 1

Hard freezes kill fleas, but it takes extended cold weather, dry weather. In the US, fleas tend to disappear in portions of northern states that 4 or more solid months of winter weather that is often well-below freezing - places like the Rocky Mountains, Northern Plains, and Sierra-Nevada mountains. Even in these cold places where fleas don't occur naturally, pets can pick up fleas when you are on vacation and establish them inside your house. In places with mild or short winters, like the Midwest, fleas are dormant in the winter, and many fleas die, but enough live through the winter for flea populations to explode in the spring.