Winter weather brings cooler temperatures – and a widespread misconception that it’s a time free from mold concerns. While many believe the season brings a reprieve from mold-related issues, the truth is far from comforting. 

The colder temperatures may slow certain biological processes, but they don’t necessarily eliminate the risks of mold and bacterial growth. As a resilient organism, mold can persist and flourish with the right conditions. Complacency in preventing mold, even in winter, can lead to overlooked issues and larger infestations. 

This raises critical questions for homeowners and renters: does mold grow in the cold? How do you prevent mold in winter? This comprehensive guide answers these questions and breaks down how bacterial growth happens, even in cold conditions. 

Can Mold Grow In The Cold

Do Freezing Temperatures Kill Mold?

Contrary to popular belief, cold weather does not kill mold. Mold spores simply lie dormant in colder temperatures but revive and grow when conditions become moist and warm enough again.

So, Does Mold Grow in the Cold?

Although winter is not humid like summer, it can create conditions inside your home that promote bacterial growth.

So, can mold grow in freezing temperatures? Rather than the low temperature, mold grows during winter because of the conditions typically found in heated homes during the season: a cozy mixture of warmth and moisture. The same systems designed to keep us comfortable – central heating and tightly sealed insulation – can inadvertently create ideal environments for mold to prosper. 

What Types of Mold Grow in the Winter?

Unlike their warm-weather-loving counterparts, certain molds have adapted to grow in colder conditions, making them a genuine winter concern. Understanding the types of mold prevalent in winter is vital to preventing and managing mold-related issues in your home during this season. 


This common indoor mold doesn’t take a break because of the cold. It can grow on wet surfaces like fabrics, carpets, and wood during winter, and are typically brown to blackish-brown or greenish-gray. 

Where to find Cladosporium: 

  • On window frames and sills 
  • In damp basements 
  • On wallpaper and painted surfaces


Another type that can make its presence felt in winter is Alternaria. It typically finds its way indoors before winter and can persist if the conditions are right, such as in areas with leaks or poor insulation. It usually appears gray or black and can spread further with increased use of humidifiers and poor ventilation in bathrooms and kitchens. 

Where to find Alternaria: 

  • In bathrooms and kitchens
  • In damp basements
  • In damp attics


Often residing within HVAC systems and insulation, Aspergillus can become a winter-time worry. Cranking up the heat can distribute mold spores throughout your living space and spread the contamination further. 

Where to find Aspergillus:

  • Inside heating, ventilation, and air condition systems 
  • In or under wet or damp carpets
  • On walls or insulation where water damage has occurred


Famous for its role in antibiotic production, Penicillium can also be a nuisance in homes during winter. It can survive in temperatures ranging from 44 to 95 degrees Fahrenheit and spread quickly, causing various respiratory problems. 

Where to find Penicillium: 

  • On fabrics, including drapes and upholstery 
  • In basements or attics with old storage boxes 
  • Around leaky pipes, roofs, or windows 

Mold on Windows: Why Does Mold Grow on Windows and What Can Be Done About It?

The combination of increased indoor humidity and decreased ventilation creates the perfect breeding ground for mold, especially on windows. Mold on windows not only spoils your home’s aesthetics but also poses health risks by reducing indoor air quality. 

Causes of Mold on Windows 

When warm, moist air inside meets cold window surfaces, condensation forms, creating an environment where mold can thrive. Gaps or flaws in window insulation can also allow moisture to accumulate and mold to grow. Finally, daily activities like cooking, showering, and drying clothes indoors can raise humidity levels, increasing the risk of mold on windows. 

Preventing Bacterial Growth on Windows 

Keeping your windows mold-free entails following these fundamental tips: 

  • Regulate indoor humidity. Use dehumidifiers to maintain optimal indoor humidity levels and keep vents running while using bathrooms and kitchens to expel humid air. 
  • Improve window insulation. Seal gaps or cracks around windows to prevent moist outdoor air from getting in. It’s also a good idea to invest in heavy curtains or consider double-glazing to create an additional barrier against the cold. 
  • Enhance air circulation. Use ceiling and oscillating fans to help distribute air throughout the room. It’s also recommended to open windows briefly on milder days to let fresh air in and stale, moist air out. 

Health Concerns With Mold Exposure

For some people, mold can cause various immediate health issues, particularly affecting respiratory health. These may include: 

  • Nasal stuffiness 
  • Throat irritation 
  • Coughing or wheezing 
  • Eye irritation 
  • Skin irritation 

Those with allergies may experience heightened reactions, with symptoms such as sneezing and runny nose becoming more pronounced in the presence of mold. Ultimately, chronic mold exposure can lead to more severe health concerns, including: 

  • Asthma in susceptible individuals 
  • Persistent respiratory infections 
  • Allergic reactions 
  • Headaches
  • Dizziness
  • Difficulty concentrating

How To Prevent Winter Mold Issues  

Now that you have a better understanding of how mold can grow indoors during winter, remember that preventing winter mold issues is all about eliminating the conditions favorable to bacterial growth. Here are some preventative measures worth adding to your to-do list for a mold-free home this season. 

Regulating Indoor Climate 

  • Maintain stable indoor temperatures. Consistent indoor warmth can deter condensation and, consequently, mold from forming on cold surfaces. 
  • Utilize dehumidifiers and proffer ventilation. Strategically placed dehumidifiers and good airflow can significantly reduce indoor moisture levels, making your home less hospitable to mold. 

Insulation and Sealing 

  • Ensure walls and windows are well-insulated. Proper insulation helps maintain even temperatures on surface areas, eradicating the cold spots where moisture condenses. 
  • Seal cracks and leaks to keep dampness out. Sealing up any openings where moisture can enter prevents water accumulation that mold needs to grow. 

Regular Maintenance and Cleaning 

  • Check for leaks and condensation buildup. Checking for water infiltration and condensation regularly helps you catch and address mold-friendly situations early on. 
  • Clean and dry wet surfaces promptly. Drying wet areas is a simple but critical step that removes the moisture that mold spores need to germinate. 

Proper Ventilation

  • Air out your home, even in cold weather. Letting fresh air in can disrupt the stale, humid conditions that mold spores favor. 
  • Use exhaust fans in bathrooms and kitchens. These appliances can expel moist air directly, preventing it from settling and promoting bacterial growth. 

Common Areas for Winter Mold 

Identifying mold during winter can be tricky as it may be more hidden than during other seasons. Learning which areas of your home are most susceptible can help you catch contaminations early, prevent their spread, and minimize damage. 

  • Attics

Poor insulation and ventilation in attics can create pockets of moisture, which promote bacterial growth. Make sure to inspect the space for any signs of attic mold, leaks, or condensation, and ensure proper insulation. 

  • Basements 

Basements are notorious for high humidity levels. Regularly check for water seepage, cracks in the foundation, and dampness. Using dehumidifiers also helps maintain optimal humidity levels and prevent basement mold

  • Crawlspaces 

Often overlooked, crawl spaces can harbor mold due to inadequate ventilation. Ensure proper airflow and consider installing a vapor barrier to prevent moisture buildup. 

  • Window Sills and Frames 

Cold outdoor temperatures that meet warm indoor air create condensation on windows. Regularly clean and inspect window sills and frames for any signs of mold, especially in bedrooms and living areas. 

  • Closets 

Mold can thrive in dark, enclosed, and undisturbed spaces like closets. Keep them well-ventilated and avoid overcrowding to promote air circulation. 

Can You Remove Mold on Your Own?

Discovering mold in your home can be unsettling, but minor contaminations can be addressed by using mold-killing solutions, disposing of mold-infested materials, and maintaining an indoor humidity below 60%. 

However, if you suspect extensive mold contamination or have a recurring mold problem despite your efforts, it’s best to seek professional help. Certified mold removal experts like Restoration 1 have the knowledge and equipment to assess and address mold problems, ensuring a safe and thorough cleanup.  

Stay Mold-Free Through the Seasons With Restoration 1

While winter may feel like a time to relax on mold vigilance, it’s crucial to remember that the cold season doesn’t mark the end of potential bacterial growth. On the contrary, winter can be a prime time for indoor mold issues.  

By understanding how mold operates in cold weather, taking active preventative measures, and getting expert help should an infestation arise, it’s possible to keep your home mold-free throughout the year. Remember, mold is not just an aesthetic concern – it can pose serious health risks. Staying vigilant and keeping your indoor environment hostile to mold year-round are critical to preserving a safe and healthy living environment. 

If you’re already dealing with bacterial contamination, take comfort in knowing that Restoration 1 is here to help return your property to normal. Our certified professionals implement proven containment methods, safety measures, and engineering controls to remove mold and keep it from returning. Contact us today to take the first step toward reclaiming a mold-free home.