Seasonal Factors for Radon Levels

Radon levels tend to fluctuate depending on environmental factors, which can change based upon the time of the year. In Wisconsin, we know there are four distinct seasons. The fall tends to have mild to cool temperatures with occasional rain and thunderstorms. The winters are wet and snowy paired with below freezing temperatures, for a minimum of three months. The spring months have a broad spectrum depending on the year, and summers in Wisconsin usually get 2 months of hot temperatures with some moderate to severe storms.

Fluctuating weather patterns will often result in fluctuating radon levels in homes. There isn’t always a distinct season where radon levels will be lower or higher, although they tend to be the highest in the winter as this season typically has the most contributing factors. Below we will discuss the factors that contribute to fluctuating radon levels, and categorize them by the season they are most prevelant.


Winters in Wisconsin consist of harsh conditions with large snowfall and severe freezing temperatures. Homes do all they can to stay warm. As air gets warmer it becomes less dense, which is why they say warm air rises. As warm air is traveling through the home, it escapes through an opening like a chimney. This creates a vacuum effect, sucking the cool air from the outside into the home to balance the air that comes out from the chimney. More air being pulled into the home from the outside can bring in higher concentrations of radon.

Another factor that effects radon levels in the winter season are ice and snow barriers that cover the ground. Radon is not able to travel through ice or snow, as it would normally diffuse through the top layer, and into the atmosphere. Instead, the radon stays trapped in the ground, and looks to release though cracks and crevices in the foundation of a home.

The last factor that is more prevalent in cold winter months compared to hot summer months is the seal tight nature of a home during winter. In the summer, homeowners tend to open up their windows, allowing airflow to go in and out of the home. In winter, windows and other openings remain shut, which keeps the air that could contain a higher concentration of radon inside the home.


Rain and severe storms can stir up the soil and cause more radon to be released during these seasons. More radon being released into the soil can eventually lead to increased levels of radon accumulating in a home during the summer months. Similar to the winter, large air conditioning units that run in summer months create a vacuum effect that sucks air from the outside into the home. If there are heavy storms or rainfall, there can be more radon in the air, which can eventually end up in the home.

Temperature fluctuation, which can be common in Wisconsin in any season other than winter (which is ALWAYS cold) affects the atmospheric pressure, leading to the release of more radon in the air. As a result, this can bring more radon into a home through the air vacuum, or through cracks in the foundation or siding.

In summary, there isn’t a clear answer towards whether or not radon levels are higher or lower in the summer or winter seasons. What’s important to understand is how the environmental factors contribute to the fluctuating levels of radon in a home. The best radon mitigation strategies are to find ways to increase airflow in your home and seal up the cracks in floors, plaster, foundations, and other areas. The ideal solution is to have a professional install a radon mitigation system to prevent increased levels of radon in your home. American Radon Removal is your #1 choice in the Racine and Kenosha area for radon mitigation systems and strategies. We’d love to hear from you and help you keep your radon levels below 1.9 pCi/L in your home!