When temperatures rise, the body sweats, and the liquid released through the skin evaporates to regulate body heat. In humid conditions — common in Puerto Rico — sweat evaporates less effectively, which increases the risk of heat-related illnesses.
Heat exhaustion and heat stroke are classified as illnesses by the Puerto Rico Department of Health and the U.S. Centers for Disease Control and Prevention (CDC).
Heat exhaustion and heat stroke are linked to environmental temperature, but vulnerability to these conditions varies depending on factors such as age and overall health. Heat exhaustion happens when the body loses a large amount of water and salts. In contrast, heat stroke occurs when the body can no longer regulate its internal temperature, according to the Puerto Rico Public Health Trust, a non-profit organization. In both cases, humidity, sun exposure, wind, physical activity, clothing, and personal risk factors play a critical role.
It is important to watch for symptoms and take precautions when heat advisories are issued. The Department of Health runs an epidemiological surveillance system for heat-related illnesses, along with another monitoring system that tracks patterns of illness and alerts experts about possible increases. Currently, only 15% of hospital emergency rooms and Diagnostic and Treatment Centers report visits related to heat or sun exposure to this system.
The National Weather Service (NWS) is responsible for issuing advisories and alerts. The regions with the most heat-related visits from January to July 2025 were Bayamón, Caguas, and the San Juan metropolitan area, according to the Department of Health’s report on heat-related events. Heat index levels have risen in recent years, not so much because of higher temperatures but because of humidity, Carlos Anselmi Molina, of the federal NWS, explained in an interview with the Centro de Periodismo Investigativo (CPI).
The last two years have been the hottest on record worldwide. In Puerto Rico, September 2024 became the hottest month since 1898, with an average temperature of 86.1°F, according to the NWS.
Courtesy NWS
NWS heat warnings are usually aimed at coastal towns. A warning is issued one to three days before dangerous heat conditions are expected and remains in effect until the risk decreases. Urban areas face particular risks because of heat islands created by urbanization, landscape changes, and population density, according to the Committee of Experts for Puerto Rico’s Climate Change Mitigation, Adaptation, and Resilience Plan.
Children, adults over 65, people with chronic illnesses, those who are overweight, and people who work or exercise outdoors are most vulnerable to heat waves, according to the CDC.
The Climate Change Plan acknowledges the health risks of increasing heat waves and outlines measures to protect vulnerable populations. It identifies the electrical power grid — on which indoor cooling often depends — as the most critical factor, noting that it has failed to meet growing energy demand.
From a policy standpoint, the plan recommends creating cooling centers in every municipality, retrofitting disadvantaged homes, offering renewable energy incentives for solar panel installation, and implementing a system to monitor the health effects of extreme weather. Although these measures have been under legislative consideration since the previous term, they have not been approved.
In 2024, the Puerto Rico Public Health Trust launched an educational campaign to help residents prepare for and prevent risks associated with extreme heat advisories. Karen Andújar, project supervisor, and Melanie Rodríguez, environmental project manager, emphasized the importance of seeking cool or air-conditioned spaces, reducing physical activity during peak sunlight hours, avoiding the use of ovens and stoves, and limiting alcohol and caffeine consumption. They shared these recommendations during a heat wave panel at Caribe Fest 2024, an event organized by the CPI that brought together experts from multiple fields.
Symptoms
Heat Exhaustion
- Weakness or dizziness
- Excessive sweating
- Muscle cramps
- Cool, pale, and moist skin
- Rapid, weak pulse
- Nausea or vomiting
Heat Stroke
- Throbbing headache
- Lack of sweating
- Loss of consciousness
- Hot, red, dry skin
- Rapid, strong pulse
- Nausea or vomiting
What to Do
The Department of Health and the National Weather Service recommend learning the signs of heat exhaustion and heat stroke and taking preventive measures. The first symptoms are often muscle cramps, which, if left untreated, can lead to severe heat stroke. If someone shows signs of heat exhaustion or heat stroke:
Move them to a cool place immediately, even before trying hydration.
- If the person is conscious and able to swallow, give them small sips of water. Electrolyte drinks, if available, are also helpful.
- Use active cooling methods, such as applying cold, wet towels, giving cold showers, or laying the person down with legs elevated to promote circulation.
- If symptoms of heat stroke persist, seek immediate medical care and use more intensive cooling measures, such as applying ice packs to the neck, armpits, and abdomen.
General Preventive Measures
- Hydrate: Drink water frequently, before feeling thirsty, and avoid alcohol or caffeine.
- Avoid Sun Exposure: Limit outdoor activities from noon to 4 p.m., when the sun is strongest, and stay in shaded or air-conditioned areas if possible.
- Clothing: Wear loose, light-colored, breathable clothing made of fabrics like cotton. The Department of Health warns against tight or synthetic clothing, which can raise body temperature.
- Additional Measures: Use broad-spectrum sunscreen with UVA/UVB protection, avoid heavy meals, and watch for heat-related symptoms.
For Children
Children have faster metabolisms and less ability to regulate body temperature, making them more susceptible to heat illness.
- Choose shaded areas for outdoor play.
- Schedule outdoor activities for the morning or late afternoon.
- Keep children hydrated, in lightweight, light-colored clothing, and limit direct sun exposure.
- Never leave a child alone in a parked car: interior temperatures can rise by 20°F in under 10 minutes, even with windows open.
For Adults 65 and Older
Older adults often take medications or undergo treatments that affect the body’s ability to regulate temperature. Caregivers and health professionals should remain alert for signs of dehydration or overheating.
For the Home
- Limit the use of ovens and stoves.
- Close curtains on sun-facing windows in the morning and afternoon.
- Maintain cross-ventilation by opening windows or doors to create airflow.
- Check on those at higher risk, such as children, older adults, and people with chronic illnesses.
- If possible, use a dehumidifier in the most frequented rooms.
For Work
- Keep hydrating drinks, like water or electrolyte beverages, on hand, and drink regularly.
- If working outdoors: Wear light, breathable clothing, protect yourself with hats and sunscreen, take frequent breaks in shaded or ventilated areas, and reschedule work during cooler hours if possible.
- If working indoors: Stay in well-ventilated spaces, use fans or air conditioning, and ensure adequate cooling.
Sources: Puerto Rico Public Health Trust, Medline Plus, Centers for Disease Control and Prevention, Puerto Rico Department of Health, Heat.gov.
This translation was generated with the assistance of AI and reviewed by our editorial team to ensure accuracy and clarity.
