Facebook Pinterest X Email Winter conditions create an environment where viruses spread more easily and immune defenses can become weakened. "Put on your hat, or you’ll catch a cold!" "Don’t go outside with wet hair — you’ll get sick!" If you’ve ever heard or said something like this, you’re not alone. It’s a widespread belief that cold temperatures cause colds. But is that actually true? In this article, we’ll unpack the science behind the increase in illness that we see during the colder months and discuss how to support your family's immune health. Does Cold Weather Really Make Us Sick? The simple answer? No. Cold temperatures themselves don’t make you sick (1) — viruses and bacteria do. The more complex answer? Yes and no. Colds, the flu, RSV, and other seasonal illnesses are caused by viruses, not by chilly air. You can’t “catch” a cold just from being outside without a jacket. However, cold weather does create an environment where viruses can spread more easily, and exposure to cold temperatures may cause your body to be more susceptible to these viruses (1). Let’s take a look at the contributing factors: Illness Increases With More Time Indoors Colder weather tends to equate to more time spent indoors with windows closed, limiting fresh air circulation. Schools, daycare centers, and other indoor gathering spaces can become hotspots for sharing germs because of the close contact, shared surfaces, and less ventilation. This makes it easier for viruses to spread from person to person, especially among kids who are in constant contact with peers and shared objects (2). To learn about what to do after exposure to a sick person, read this article: What to Do After Exposure to a Sick Person: Immune Support Tips for Families Viruses Thrive in Cold, Dry Air Many respiratory viruses, like the flu and RSV, survive longer in cooler, drier environments (3). The dry air inside heated homes, schools and workplaces can also dry out the protective mucus in the nose and throat (4), making it easier for viruses to invade, bringing us to our next point. Dry Air Can Contribute to Weaker Mucosal Barriers The mucosal lining in the nose and respiratory tract acts as the body’s first line of defense against germs (5). It’s coated with a thin layer of mucus that traps viruses, bacteria, and other particles, preventing them from entering the body. In cold, dry air, this protective mucus can dry out and become less effective at trapping pathogens. Additionally, the tiny hair-like structures called cilia, which help move mucus and trapped germs out of the airways, don’t function as well in dry conditions (6), potentially making it easier for viruses to linger and invade. Prolonged dryness could even cause tiny cracks in the mucosal tissue, creating openings for viruses to slip through more easily. To learn more about using nasal sprays for upper respiratory protection, read this article: How To Buy Or Make Antiseptic Mouth Rinses and Nasal Sprays Low Vitamin D Levels Affect Immune Health Shorter days and less time outside in winter mean kids get less sunlight, leading to lower vitamin D levels (7). Sufficient vitamin D intake is important for immune health (8), and low levels have been linked to a higher risk of respiratory illnesses (9). While some vitamin D comes from foods like fatty fish and egg yolks, sunlight is the main source, making supplementation especially helpful during colder months. To learn more about vitamin D supplementation, read this article: Better Together: Vitamins D3 & K2 Cold Exposure Impacts the Immune System While cold temperatures don’t directly cause illness, they can influence immune function (10). This remains a topic of ongoing research, but we know that cold exposure triggers stress responses in the body, increasing hormones like norepinephrine and cortisol, which can temporarily alter immune activity (10). Interestingly, brief cold exposure may stimulate immune responses, but prolonged exposure — especially when combined with physical exertion — may suppress immunity (10), potentially making you more prone to getting sick when exposed to germs. Common Myths About Cold Temperatures and Illness Let’s dispel some common myths about cold exposure and sickness: Myth: Going outside with wet hair will make you sick.Fact: Wet hair might make you feel cold, but you won't get sick unless you’re exposed to a virus. Myth: Not wearing a hat will cause an ear infection.Fact: Ear infections are caused by bacteria or viruses, not by cold air. However, keeping your ears covered in extreme cold can prevent discomfort and frostbite. Myth: You can “catch” a cold from being outside in the cold.Fact: The common cold is caused by a viral infection. You need to come into contact with a virus to get sick, regardless of the weather. Should You Worry About Your Kids Being Cold? While cold weather doesn’t cause illness in and of itself, extreme cold can still be dangerous, especially for infants and young children. As a general rule, babies should wear one more layer than adults to maintain warmth and comfort. Fingers, toes, and ears are especially vulnerable to the cold, so check them frequently when outside. Watch for signs of frostbite, such as numbness and grayish or pale skin, as well as signs of hypothermia, which can include intense shivering, slurred speech, drowsiness, and confusion. How to Support Your Family’s Immune Health in Cold Weather While you can’t completely prevent your kids from getting sick, especially if they’re in school or daycare, you can support their immune systems to help them fight off infections more effectively. To learn more about what to expect in terms of sickness frequency in kids by age, read this article: Does My Child Get Sick Too Often? Understanding Sickness Frequency in Children Focus on providing your kids with a nutrient-dense diet that includes plenty of colorful fruits and vegetables rich in vitamins A, C, and D, as well as zinc to support immune function. For tips on sneaking nutrients into picky kids, read this article: Nutrient & Calorie Dense Foods That Help Underweight Kids Thrive. It is important to ensure kids stay hydrated by drinking plenty of fluids and you may also wish to consider using humidifiers in bedrooms to help keep mucosal barriers moist and effective at trapping germs. Prioritize good sleep, as rest is when the immune system does its best repair work (11). For more sleep tips for infants and kids, read this article: 9 Reasons Your Kids Aren’t Sleeping (And How To Help) Getting outside, even on chilly days as long as you’re bundled up, supports immune health through physical activity and natural vitamin D production from sunlight. Finally, good hygiene habits, like regular handwashing, also help reduce germ exposure (12). Be mindful of harsh soaps that can strip delicate skin, especially during the dry months, and seek out gentle moisturizers. For more detailed guidance on supporting the immune system during winter, read this article: Winter Immune Support For All Ages. Summary Cold weather itself doesn’t cause illness — viruses and bacteria do. However, winter conditions — like spending more time indoors; exposure to cold, dry air; and lower vitamin D levels — create an environment where viruses spread more easily and immune defenses can be weakened. To support your family’s immune health during colder months, focus on a nutrient-dense diet, good hydration, plenty of sleep, outdoor activity for fresh air and vitamin D, and consistent hygiene practices. While you can’t prevent every illness, these strategies can help keep your family healthier through the winter. If you liked this article, please share! Facebook Pinterest X Email PRODUCTS MENTIONED IN THIS ARTICLE See Product See Product See Product See Product See Product See Product See Product See Product See Product See Product SHOP & EARN REWARDS. JOIN TODAY! RELATED ARTICLES How To Calculate Supplement Dosages For Kids Read more Choosing A Supplement Delivery Method For Your Family Read more Baby Skin Care 101 Read more 5 Common Toxins In Skin Care Products Read more Ultra-Processed Foods: What Are They, & How Are They Affecting Kids? Read more Understanding & Supporting A Healthy Inflammatory Response Read more Better Together: Vitamins D3 & K2 Read more References: Mourtzoukou EG, Falagas ME. Exposure to cold and respiratory tract infections. Int J Tuberc Lung Dis. 2007 Sep;11(9):938-43. PMID: 17705968. Dixit AK, Espinoza B, Qiu Z, Vullikanti A, Marathe MV. Airborne disease transmission during indoor gatherings over multiple time scales: Modeling framework and policy implications. Proc Natl Acad Sci U S A. 2023 Apr 18;120(16):e2216948120. doi: 10.1073/pnas.2216948120. Epub 2023 Apr 10. PMID: 37036987; PMCID: PMC10119995. Paynter S. Humidity and respiratory virus transmission in tropical and temperate settings. 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Vitamin D deficiency prevalence in summer compared to winter in a city with high humidity and a sultry climate. Endokrynol Pol. 2011;62(3):249-51. PMID: 21717408. Martens PJ, Gysemans C, Verstuyf A, Mathieu AC. Vitamin D's Effect on Immune Function. Nutrients. 2020 Apr 28;12(5):1248. doi: 10.3390/nu12051248. PMID: 32353972; PMCID: PMC7281985. Hughes DA, Norton R. Vitamin D and respiratory health. Clin Exp Immunol. 2009 Oct;158(1):20-5. doi: 10.1111/j.1365-2249.2009.04001.x. PMID: 19737226; PMCID: PMC2759054. LaVoy EC, McFarlin BK, Simpson RJ. Immune responses to exercising in a cold environment. Wilderness Environ Med. 2011 Dec;22(4):343-51. doi: 10.1016/j.wem.2011.08.005. Epub 2011 Oct 7. PMID: 21982757. Besedovsky L, Lange T, Born J. Sleep and immune function. Pflugers Arch. 2012 Jan;463(1):121-37. doi: 10.1007/s00424-011-1044-0. Epub 2011 Nov 10. PMID: 22071480; PMCID: PMC3256323. Centers for Disease Control and Prevention. (16 Feb 2024). About handwashing. 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