There's A New Risk Factor For Stroke & Heart Health — What To Know
When you think about stroke risk, you probably think about blood pressure, diet, and exercise. But a new scientific statement1 from the World Stroke Organization adds another factor to the list: climate instability.
Temperature swings, wildfire smoke, humidity shifts, air pressure changes, and overlapping weather extremes can all affect your vascular system.
And while you can't control the weather, you can take steps to protect yourself, especially if you're already prioritizing heart health.
How climate instability affects your body
The key insight from this research isn't just that extreme weather is dangerous—it's that climate instability itself puts stress on your cardiovascular system.
Cold exposure and rapid temperature swings increase blood pressure and activate your body's stress response.
Heat, on the other hand, causes dehydration and makes your blood thicker.
Both of these changes can strain your blood vessels and raise stroke risk.
Air pollution adds another layer. Wildfire smoke and dust storms deliver tiny particles that trigger inflammation and affect how your blood vessels function, which can increase the chance of clots forming.
Temperature extremes & air pollution linked to higher stroke rates
The statement reviewed studies from around the world and found that cold exposure, temperature variability, and extreme thermal events were most consistently linked to increased stroke risk. While cold effects were generally stronger, the researchers noted that heat-related stroke risks have been increasing over time as global temperatures rise.
Ischemic stroke (the most common type, caused by a blood clot blocking an artery in the brain) appears to be particularly affected by these environmental shifts.
What makes this especially concerning is how overlapping weather conditions can compound the risk. For example, the statement cited research showing that extreme cold combined with high humidity more than doubled stroke risk compared to extreme cold alone.
Wildfire smoke also emerged as a clear risk factor. One study found that same-day ischemic stroke hospital admissions rose with each increase in wildfire-related fine particulate matter, even after accounting for other sources of air pollution.
Older adults, people with metabolic conditions like diabetes, and communities with limited resources to adapt face the highest risk from these environmental factors.
How to protect yourself when the weather works against you
You can't control your environment, but you can build habits and systems that help your body handle whatever comes. Here's how to take charge of your risk:
Track air quality and weather alerts: Get in the habit of checking air quality indexes (AQI) and weather forecasts, especially during wildfire season, heat waves, or cold snaps. Apps like AirNow or your phone's built-in weather app can send you alerts when conditions are risky. On those days, skip intense outdoor workouts and stay indoors when possible.
Stay well-hydrated: When you're dehydrated, your blood gets thicker, which raises the chance of clots. During extreme heat, your body needs more fluids than usual. Water is essential, but adding electrolytes helps your body hold onto fluids and supports your heart.
Regulate your temperature: In extreme heat, find air-conditioned spaces, wear light clothing, and take cool showers. In cold snaps, layer up and avoid sudden exposure to freezing temperatures. The goal is to help your body avoid the strain that comes with rapid temperature shifts.
Invest in clean indoor air: You can't always avoid outdoor air pollution, so focus on what you can control: your home. A quality air purifier with a HEPA filter can significantly cut down on particles from wildfire smoke, dust, and other pollutants.
Review medications with your doctor: Some medications, including blood pressure drugs and diuretics, may need adjusting during extreme weather. Heat can make diuretics work too well, increasing your risk of dehydration. If you take heart or blood pressure medications, talk to your doctor about how to manage them during heat waves or cold snaps.
Have an extreme weather plan: Think of this like a health emergency kit. Know where your nearest cooling center is. Keep backup medications handy. Have a plan for clean indoor air, whether that's an air purifier or knowing which rooms in your home have the best airflow.
Build a strong foundation: Environmental triggers build on your existing risk level. The stronger your cardiovascular foundation, the more resilient you'll be. That means focusing on managing your blood pressure, regular movement, a nutrient-rich diet, quality sleep, and stress management.
The takeaway
Climate instability is emerging as a real contributor to stroke risk. By tracking air quality, staying hydrated, managing your temperature, and building a strong cardiovascular foundation, you can offset some of that environmental risk. You can't control the weather, but you can control how prepared you are for it.
