# What Hot Weather Does to Your Body
Heat stress affects every system in your body, from your cardiovascular function to your cognitive performance. When temperatures climb, your body launches a coordinated response designed to keep your core temperature stable, but this process has limits and vulnerabilities.
Your body cools itself primarily through perspiration and increased blood flow to your skin. This diverts blood away from your organs and muscles, which is why heat makes you feel fatigued. Your heart works harder to pump blood to the skin surface for cooling, increasing your heart rate and straining your cardiovascular system. Prolonged heat exposure elevates body temperature and can lead to heat exhaustion, characterized by dizziness, nausea, and weakness, or heat stroke, a life-threatening emergency where your body's cooling mechanisms fail entirely.
Heat also impairs mental function. Studies show that elevated core temperature reduces cognitive processing speed and decision-making ability. Physical performance declines as muscles fatigue faster and dehydration thickens your blood, reducing oxygen delivery.
Not everyone experiences heat equally. Older adults face higher risk because their bodies produce less sweat and respond more slowly to temperature changes. People with cardiovascular disease, diabetes, or respiratory conditions struggle to regulate temperature effectively. Certain medications, including some antidepressants and antihistamines, impair sweating or increase heat production.
Children and infants also sit at higher risk. Their bodies generate heat faster and cool themselves less efficiently than adults. Outdoor workers, athletes, and people experiencing homelessness face extended heat exposure without adequate protection or recovery time.
Preventing heat-related illness requires deliberate action. Stay hydrated throughout the day, not just when thirsty. Seek air-conditioned spaces during peak afternoon heat. Wear light, loose clothing. Monitor vulnerable family members and neighbors. If someone shows signs of heat exhaustion, move them to shade