Is asthma worse in summer or winter?

Asthma is a common chronic condition that affects the airways and lungs. In response to certain triggers, the airways become inflamed and narrowed, making breathing difficult. Some common triggers include pollen, exercise, and even weather changes.

You may find that your asthma worsens in the summer or winter. This is because certain things associated with these seasons, such as higher pollen counts in the summer or colder air in the winter, may be triggers for your asthma. People might refer to this as seasonal asthma.

Triggers are different for everyone, so some people may notice their asthma is worse in winter, while others may find it worsening in summer.

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How does summer affect asthma?

For some people with asthma, the summer period may affect your symptoms the most. There may be several reasons for this.

Pollen counts

Pollen is a fine substance in the air produced by seeds from flowering plants, trees, and grasses and is a common trigger of allergies and asthma. Pollen counts are typically higher in the warmer months, although some plants release pollen year-round.

For many people, there is a close link between seasonal allergens and asthma flare-ups. People may refer to this as seasonal or allergic asthma. According to some 2019 research, pollen is one of the main causes of seasonal asthma and one of the most common asthma subtypes worldwide.

Hot weather

Summer weather may be hotter than usual and dry or humid. Both of these types of heat may worsen your asthma.

According to some 2024 research, there is a link between high humidity levels and increased asthma symptoms. This is because the increased moisture in high humidity can disrupt the barrier in your airways, making it easier for allergens to get in and reducing mucus clearance from your lungs.

This may increase inflammation and airway narrowing, causing asthma symptoms.

At the other end of the scale, dry heat, with too little moisture in the air, may irritate your airways and worsen symptoms.

Increased exercise

As summer comes with warmer weather and longer daylight hours, you may be more likely to spend more time outdoors. These conditions may be more favorable for physical activities such as hiking, swimming, or biking.

However, while slowly increasing your exercise level can be helpful for asthma in the long term, increased exercise may be a trigger for an asthma flare-up. This is known as exercise-induced asthma. It’s important to bear this in mind if you plan to increase your exercise levels in the summer.

How does winter affect asthma?

You might notice that your asthma symptoms worsen in the winter.

Cold weather

Winter is generally associated with cold weather. According to some 2018 research, cold, dry weather is likely to worsen asthma and increase symptoms. This is because the dry, low-humidity air can irritate and narrow your airways.

A 2022 paper suggests that this effect is linked to how severe your asthma is and how well you manage it. For example, someone with more severe, unmanaged asthma will experience more effects of cold weather than someone with mild, well-managed asthma.

Indoor allergens

In the winter, you may be more likely to spend time indoors with the windows closed, leading to limited air circulation. This can increase your exposure to indoor allergens, such as:

• dust mites
• mold
• pet dander

These allergens may trigger asthma, so you may notice that spending time indoors in the winter worsens your symptoms.

Common winter viruses

While you can catch a cold or the flu at any time of year, these viruses tend to circulate in the winter months. These viruses may also worsen your asthma symptoms.

Cold and flu viruses cause respiratory illnesses, meaning they affect your lungs and airways. When you have asthma, your airways are already very sensitive. If you have asthma, you may be at higher risk of complications from the flu.

Is asthma worse in summer or winter?

The key takeaway is that asthma is different for everyone. For people sensitive to pollen, for example, summer may worsen asthma symptoms the most. For people sensitive to cold air, winter may worsen symptoms.

It may help to keep a diary of your symptoms at different times of the year. This can help you figure out when your symptoms flare up the most and prepare for the different seasons.

Managing asthma

Regardless of the season, it’s important to manage your asthma to avoid flare-ups and serious complications. Treatment plans for asthma usually include long-term medications and short-acting ones to use during a flare-up.

For example, during an asthma attack, short-acting beta 2-agonists (SABAs) can help open the airways and reduce swelling. Examples of these include albuterol (ProAir) and levalbuterol (Xopenex). You generally take these via an inhaler.

Long-acting beta 2-agonists (LABAs) may also be an option. These include salmeterol and formoterol (Performist), or a combination of the two, which you also take via an inhaler. They last longer, but they also take longer to work than SABAs, so they are not suitable for use during an asthma attack.

If you have asthma, a doctor will help create a treatment plan that’s right for you.

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Summary

Asthma is a respiratory condition that affects your airways. It can affect everyone differently but usually flares up in response to different environmental triggers, which may differ at different times of the year.

For example, increased pollen counts and hot, humid weather in the summer may be particular triggers for some people. On the other hand, winter viruses like the flu and cold air may worsen asthma for people in the winter. No two people are affected exactly the same way.

If you want to know whether your asthma will be worse in the summer or the winter, consider keeping a diary of your symptoms to check when flare-ups are most likely. This can help you manage your condition most effectively.

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