One thing that’s well known for being around during the winter season is the flu. But why does the flu seem to kick into high gear during the winter as opposed to the summer? Contrary to (the whacky) school of thought, the rapid spread of flu during the winter isn’t caused by chemtrails sprayed by the government. Here are three reasons the flu spreads more during the winter than the summer.

Three Reasons The Flu Spreads More During The Winter than Summer Months

1. There Is Less Sunlight

During the winter there are less hours of available sunlight and that’s even more true the further away a person lives from the equator. Sunlight is one of the best ways our bodies make vitamin D. Vitamin D helps to support a stronger immune system. In fact, vitamin D deficiencies can lead to a weakened immune system. Temperatures are also much colder during the winter months so people spend more time. Spending more time inside is also something that contributes to people getting less sunlight and less vitamin D.

If you’re concerned that you might be getting to little vitamin D, you can always consider vitamin D supplementation.

2. Temperatures Are Colder

Cold is a contributing factor in a couple of ways. First of all, the virus survives longer in colder temperatures. Compared to temperatures at 43 degrees F and 90 degrees F, the flu virus was able to survive at much longer times (1). The second ways is that colder temperatures, people are more likely to spend more time inside. Spending more time inside and in closer contact with other people will increase the odds that you will get sick.

3. Air Is Drier

Winter air tends to be drier than the summer months. People on the East Coast and  the Southern portion of the United States are no stranger to the feeling of high humidity of the summer months. Flu virus particles are so small that they’re very sensitive to the amount of humidity in the air. The drier the air, the more likely the virus is to stay in the air and travel further distances (1). The more wet the air, the easier it is for the virus to attach to water molecules in the air and fall to the ground.

So, it seems that winter is the most conducive season for spreading the flu. Most medical experts argue that getting the flu vaccine is the best way to  keep from getting the flu. That decision is really up to you – the flu shot is an educated guess on the most active flu viruses and is only ten to sixty percent effective from any given year. The best way is to wash your hands, keep from touching your face, and minimize contact with other people who have the influenza virus.


1. Foster, H. The Reason For The Season: Why Flu Strikes In Winter. Harvard University: The Graduate School Of Arts and Sciences. 1 December 2014. Web. 4 February 2018.