Does exposure to cold weather make a cold worse? The scientific truth

September 22, 2025 •

4 min read

According to a 2022 Harvard Medical School study, cold temperatures can inhibit the immune response in the nasal passages, making an infection more likely. This sheds new light on the long-held question, "Does exposure to cold weather make a cold worse?" and reveals the complex interplay between viruses, temperature, and our body's defense mechanisms.

Quick Summary

Cold weather doesn't cause a cold directly, but scientific evidence shows it can weaken your nose's immune defenses and dry out membranes. This creates conditions where viruses can more easily take hold, and symptoms may feel more severe, especially with respiratory conditions.

Key Points

Not a Direct Cause: Cold weather doesn't give you a cold; viruses do. You must be exposed to a virus to get sick.
Weakens Nasal Defenses: Research shows that colder temperatures can reduce the effectiveness of immune cells in your nose, making it easier for viruses to take hold.
Favors Viral Survival: Viruses like influenza can survive longer in the cold, dry air of winter, contributing to their spread.
Exacerbates Symptoms: Dry, cold air can irritate respiratory passages, making existing symptoms like a sore throat or cough feel worse.
Promotes Indoor Spread: When it's cold, people gather indoors, leading to closer contact and easier transmission of germs.
Supportive Care is Key: Rest, hydration, and managing indoor air quality are effective strategies for dealing with a cold, regardless of the temperature.

The Surprising Science: How Cold Affects Your Body's Defenses

For generations, people have debated whether cold weather is directly responsible for catching a cold. While the common cold is caused by a virus (most often a rhinovirus), and not the temperature, recent scientific findings have added nuance to this long-held belief. Rather than being a simple cause-and-effect relationship, the cold can create conditions that make you more vulnerable to infection and may even worsen existing symptoms.

The Nasal Immune Response and Cold Temperatures

A 2022 study by Harvard Medical School researchers at Mass Eye and Ear uncovered a previously unknown immune response in the nose. This defense mechanism relies on tiny sacs, called extracellular vesicles (EVs), that are released by cells in the nasal passages to trap and kill invading viruses. The study found that when the temperature inside the nose drops by just a few degrees, the production and efficacy of these EVs are significantly reduced. This gives viruses a better chance of replicating and causing an infection.

Viral Behavior in the Cold

Beyond affecting your body's defenses, cold and low humidity environments can also favor the viruses themselves. A 2015 Yale-led study demonstrated that the common cold virus (rhinovirus) replicates more efficiently at the cooler temperatures found inside the nasal cavity (approximately 33°C or 91.4°F) than at the core body temperature (37°C or 98.6°F). Furthermore, other research has shown that the lipid coating of the influenza virus becomes more rigid in cold, dry air. This makes the virus more resilient and stable, allowing it to survive longer and spread more easily through the air.

Why Winter is "Cold and Flu Season"

So, if the cold isn't the direct culprit, why do so many people get sick during the winter? It's a combination of factors that create a perfect storm for viral transmission:

Increased indoor proximity: Cold weather naturally drives people indoors, where they spend more time in close contact. This higher concentration of people in enclosed spaces, such as schools, offices, and homes, makes it easier for respiratory viruses to spread from person to person.
Dry air and low humidity: The dry air common in winter, both outdoors and from indoor heating systems, can dry out the protective mucous membranes in your nose and throat. This compromises the body's natural barrier against germs, allowing viruses to more easily attach and invade.
Reduced Vitamin D: Less exposure to sunlight during the shorter days of winter can lead to lower levels of vitamin D. Since vitamin D is crucial for a healthy immune system, this can further weaken your body's ability to fight off infections.
Lifestyle Changes: Many people become less active and experience more stress during the winter months, both of which can negatively impact immune function.

Does Cold Exposure Worsen Existing Symptoms?

While cold exposure won't give you a cold, it can absolutely make an existing one feel worse. The cold, dry air can irritate already inflamed respiratory tissues, leading to a more pronounced sore throat and congestion. For people with pre-existing conditions like asthma, cold air can trigger bronchoconstriction, which constricts the airways and can lead to increased coughing, wheezing, and shortness of breath. Your body also expends energy to stay warm, which might temporarily divert resources from the primary immune response.

How Environmental Factors Affect Your Health


Factor	Cold Weather Environment	Warm Weather Environment
Viral Transmission	Increased due to indoor crowding and dry air aiding virus stability.	Decreased due to better ventilation and outdoor activity.
Immune Response	Can be suppressed; nasal passages less effective at fighting viruses.	Functions at optimal temperature; fewer environmental inhibitors.
Symptom Severity	Dry air can exacerbate sore throat and congestion.	Air is generally more humid, potentially easing some respiratory symptoms.
Vitamin D Levels	Often lower due to less sunlight exposure, impacting immunity.	Generally higher due to more sun exposure.

What to Do When Under the Weather

If you find yourself with a cold during the chilly season, these steps can help manage your symptoms and aid recovery:

Prioritize Rest and Hydration: Allowing your body to rest is crucial for a strong immune response. Drink plenty of fluids like water, clear broths, and herbal tea to stay hydrated and thin mucus.
Cover Up Outdoors: If you need to go outside, covering your face and nose with a scarf can help warm and humidify the air you breathe, which supports your nasal immune defenses.
Humidify Indoor Air: Use a humidifier to combat the dry air from your home heating system. This can soothe your irritated nasal passages and throat.
Wash Your Hands Frequently: This simple act remains one of the most effective ways to prevent the spread of respiratory viruses.
Consider OTC Medications: Over-the-counter decongestants, saline nasal sprays, and pain relievers can help alleviate symptoms.
Seek Fresh Air: Brief periods of fresh air can be beneficial for ventilation and symptom relief, just be sure to dress warmly.
Know When to Seek Medical Help: While most colds resolve on their own, contact a healthcare provider if your symptoms worsen, persist, or if you have an underlying health condition. For more information on cold and flu prevention, you can also consult the Centers for Disease Control and Prevention (CDC).

Conclusion: The Cold Reality

The myth that cold weather causes a cold is a misconception, but the truth is more complex. Cold temperatures and associated factors like dry air and more time spent indoors can indeed create an environment that favors viral spread and makes your body more susceptible to infection. Furthermore, cold air can exacerbate existing symptoms. By understanding these mechanisms, you can take practical steps, like dressing appropriately, staying hydrated, and maintaining good hygiene, to better prepare your body for the winter season and reduce the impact of respiratory illnesses.

Frequently Asked Questions

No, a cold is caused by viruses, not by the temperature itself. You must be exposed to the virus to become infected.

Cold, dry air can irritate your already inflamed nasal passages and throat, which can make your symptoms feel more intense. It doesn't prolong the illness but can make you feel more uncomfortable.

Wearing a coat helps your body maintain its core temperature, which supports your immune system. However, it doesn't prevent exposure to viruses. Layering up is a good strategy for comfort and health, but it's not a foolproof prevention method.

Yes, getting some fresh air can be beneficial. As long as you are dressed warmly, brief periods outside can improve your mood and potentially help with ventilation, just be mindful of strenuous activity.

Yes, the dry air from heating systems can dry out your mucous membranes, which can worsen symptoms like a sore throat or congestion. Using a humidifier can help.

Due to less sunlight exposure, many people have lower vitamin D levels in the winter. Since vitamin D is important for immune function, maintaining adequate levels is beneficial for overall health.

Some viruses, like the flu, are more stable and can survive longer in cold, dry conditions. While cold weather isn't the only factor, it contributes to an environment where viral spread is more efficient.