Why Flu Season Strikes In Winter


First, it’s a runny nose. Then a cough. Before you know it, you’re bedridden with a sore throat, fever, and aches. It’s flu season, and every year it comes without fail. But why does it come during the colder winter months? Let us explain.

When your mother told you “Bundle up, you’re going to catch a cold?” was she really onto something? Yes, and no. It’s no mystery that cold and flu season occurs during the winter months and the reasoning why that is isn’t so clear. In fact, scientists are just starting to piece together information like detectives to figure out why the flu gets so bad during the coldest time of the year. There are a few different reasons why.

Cold Air & Flu Virus

Myth: Cold weather causes you to catch the flu.

Fact: Cold weather actually doesn’t make you get sick. You might not feel great after running around in the middle of winter with no jacket on, but it’s not an activity that causes you to get ill with influenza. There is something a little bit more scientific going on.

There is a theory that the influenza virus may survive better in colder, drier climates. When it’s humid outside, water droplets in the air fall to the ground. This is because they’re heavier, right? When this happens, any viruses or germs surviving in those droplets also fall to the ground. In the winter, however, it’s a lot less humid than the dog days of summer. Therefore, water droplets in the air can survive longer and prolong the amount of time the virus hangs around. There are a few different studies on this point, so if you’re up for some additional scholarly reading, check out Palese’s guinea pig experiment. We’re also using our severe weather tracker to try and get a picture of the correlation between colder, drier weather and flu rates.

Being Indoors

Think about all the time you spend indoors. You’re inside a lot during the winter, right? When it comes down to it, germs pass between people. In the winter when the weather is cold and we’re snuggled up, we’re more likely to spread germs to one another. You don’t have to get very close to catch the flu, either. In the winter, we often keep window and doors shut to keep us warm. However, that also keeps the virus inside as well. That’s why you can catch the flu from someone in your home or office even if you’re staying far away from them. It’s in the air.

Another contributing factor that comes from being indoors during the winter is the lack of vitamin D. We get vitamin D and melatonin from the sun. Both nutrients are key players in our immune systems. In the winter, the sun sets sooner and we are less likely to spend time soaking up its rays, therefore it’s simply easier to get sick. If our bodies don’t have the right tools to fight a virus, we’re in for some trouble.

Flu Season Facts

Now that you know a little bit more about why flu season strikes in winter, let’s get you up to speed on some other flu season facts that can help you improve your Winter Weather Safety.

Flu season dates vary per year. Typically, the flu doesn’t get into full swing until December. However, it’s common to see the season start as early as October. Generally, the flu season peaks in February and ends in March.

The flu can be deadly. According to the Center for Disease Control, the flu kills between 12,000-56,000 people in the U.S. every year.

The best way to beat the flu is to stop yourself from getting it in the first place. You should get your flu shot before November, if possible. However, after then it’s still not too late. Also make sure you wash your hands, stay away from people who appear sick, and take some supplements for your immune system.