Mold is commonly thought of as a seasonal problem, and many homeowners think mold issues disappear when the weather is cold. But while temperature does affect the way mold grows, it’s a year-round problem.

Mold growing on indoor surfaces can damage your home and negatively impact your health. It’s important to be aware of how and where mold can grow in your home, even during the winter months.

Keep reading to learn the answers to the top 5 most-asked winter mold questions.

1. Can mold grow in cold temperatures?

The short answer is yes. Mold requires three things to grow: enough moisture, an adequate food source, and the right temperature. But contrary to what many people think, mold doesn’t only grow in warm environments.

Different types of molds thrive under different conditions, and some molds are more likely to grow in the winter months than others. Each type of mold has a minimum and maximum temperature ranges for growth, with many varieties of fungi thriving in environments between 60 and 80 degrees Fahrenheit. Unfortunately, the right temperature conditions for mold growth are also ideal for our comfort, and we tend to heat or cool our homes to stay within those parameters.

2. Does mold die in the winter?

Cold weather will not kill mold. Mold spores are opportunistic in the sense that they wait for the right conditions and then begin to spread. 

Extreme temperatures do not kill mold, but they can deactivate them. Even when temperatures drop below freezing, mold spores don’t die; they simply become dormant and will begin to multiply and grow again as soon as the temperature rises.

That’s why controlling the temperature alone will not solve your mold problems. The key to removing mold from your home and keeping it from popping back up is to control humidity levels and prevent the buildup of moisture.

3. Why does mold grow on windows in winter?

The fall and winter months bring precipitation and dew, and surfaces in our homes that collect moisture, like window panes, are ideal places for mold to expand and grow.

raindrops on window

Moisture collects on and around windows in the winter due to condensation, which happens when warm air hits a cold surface. When the temperature drops during the winter, the warm air in your home comes into contact with the cool glass of your window panes, depositing water vapor and leading to moisture buildup around your windows. That’s why moisture, and sometimes mold, tends to collect around windows during the colder months.

4. Do mold allergies go away in winter?

Mold allergies are common and can cause a variety of unpleasant symptoms, including sneezing and runny nose, coughing, itchy eyes, nose, throat, or skin, and watery eyes. Mold can also trigger asthma attacks in asthma sufferers who are allergic to mold.

Many people notice their allergy symptoms decrease when the temperature drops. Unfortunately, people with mold allergies often actually experience more symptoms during the winter when they’re more likely to be indoors for long periods of time. Mold allergies can be worsened by indoor heat, which can send mold spores that have collected in your ducts and other places into the air.

5. How do you prevent mold from growing in the winter?

Here’s what you can do in your home to prevent mold from growing and spreading during the winter months; these strategies will also help prevent and improve mold allergies:

  1. Try to keep humidity below 50% throughout your home at all times. 
  2. Inspect pipes and fix plumbing leaks as soon as possible to prevent water from collecting.
  3. Use mold-killing cleaners in bathrooms and areas of your kitchen where moisture collects.
  4. Avoid having carpets or rugs near windows, sinks, or other places that tend to become wet.
  5. Inspect your air ducts and change the filters on your furnace regularly.
  6. Always use a ventilation fan during showers or baths.
  7. Clean your gutters regularly to prevent moisture from building up on collected debris.
  8. Get rid of old recycled material, newspapers, and any upholstery or fabric that has been exposed to moisture.

mold in cold temperatures

Mold needs the right temperature, humidity conditions, and a food source to grow. Room-temperature conditions and organic material such as paper, cardboard, wood, and ceiling tiles are nearly impossible to remove from your home. That’s why the best way to prevent the spread of mold is to control moisture. Using dehumidifiers and a meter to test humidity levels will help stop moisture from building up and prevent mold around windows.

RELATED: Everything You Need to Know About Household Mold 

Test your home for mold and protect your home and family.

Although mold is an important component of maintaining a strong outdoor ecosystem, indoor mold can cause damage to your home and your health. Whether you’ve smelled an odd, earthy scent in your home, noticed symptoms of mold allergy, or are having trouble breathing, a professional mold inspection will provide the answers you need.

At JSE Labs, we’re dedicated to providing accurate, professional mold testing. We offer in-home inspections and testing conducted by our skilled environmental consultants. We also provide specialized in-lab testing, which allows you to collect your own sample and submit it to us.

Contact us today or give us a call at (503) 659-8338​ to check your home for mold.


Lisa Jones-Stohosky

Lisa Jones-Stohosky

Lisa started in the industrial hygiene and environmental industry in 1992 as an asbestos microscopist and began performing building inspections for asbestos, lead paint, and other hazards in 1994.

“This career has been an amazing experience, traveling for work to perform inspections both locally and abroad to locations such as Hawaii and Germany. My real love however is being in the laboratory and assisting our wonderful clients.”