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Your Environment. Your Health.

Weather Extremes

man carrying child in flooded area


Weather extremes can have adverse effects on human health, including concerns from severe heat and cold. Storms and harsh conditions, such as hurricanes and droughts, can create secondary dangers, including floods and wildfires.

NIEHS has resources on many types of events and conditions, and some are included on this webpage.

Temperature Extremes


As a result of the changing climate, heat waves are happening more often. An increased number of extreme heat days or prolonged exposure to hot temperatures can harm your health. Extreme heat is a threat to human health worldwide, according to the World Health Organization.

Heat-related illnesses include heat exhaustion, heat cramps, and heat stroke (also called sun stroke). Heat stroke, considered a medical emergency, occurs when a body's regulatory system fails to cool itself. As your body works to cool itself, blood rushes to the surface of your skin. As a result, less blood reaches your brain, muscles, and other organs, which can, in rare cases, cause brain damage or death.

Here are signs of stress from heat:

  • Dizziness
  • Fainting
  • Headache
  • Muscle cramps
  • Nausea or vomiting
  • Weakness

Read about extreme heat protection tips from the Centers for Disease Control and Prevention.


Extremely cold air is seasonal in part of the U.S., affecting millions of people. It can lead to health problems and ice-related dangers, such as falls and car accidents. In cold weather, people without adequate shelter or who are stranded may have health emergencies.

Cold air acts as a vasoconstrictor, which means it narrows blood vessels, increasing risk of heart attack and strokes. Blood pressure tends to rise with exposure to cold.

Hypothermia is a condition in which the body's internal temperature falls too low. Acute hypothermia occurs with immersion in cold water or exposure to cold weather. Prolonged exposure to even mild cold can cause hypothermia. Signs that your body is not handling cold well include stiffness in the neck, arms, and legs.

Older adults, due to changes that come with aging, may lose body heat faster than younger people. The National Institute on Aging offers tips for Cold Weather Safety for Older Adults.

For people of all ages, the Centers for Disease Control and Prevention offers a prevention guide for dealing with extreme cold.

What is NIEHS Doing?

NIEHS Efforts

  • Climate Change and Human Health – As the planet warms, oceans expand and the sea level rises, floods and droughts become more frequent and intense, and heat waves and hurricanes become more severe.
  • Disaster Research Response – NIH created a national framework for research on the medical and public health aspects of disasters and public health emergencies. The DR2 program provides tools, training, funding, and other support to empower human health research in response to disasters and public health emergencies.
  • Flooding and Hurricanes: Fugitive Chemical Health Risks – Coastal storms heighten the potential for hazardous chemicals to spread due to facility damage, storm surge, and flooding — creating "fugitive" chemicals.
  • Hurricane Sandy Response Report (11MB) – In the aftermath of Hurricane Sandy, under the National Disaster Recovery Framework, the NIEHS Worker Training Program prepared and trained cleanup workers, homeowners, and volunteers about the hazards that can be found in impacted areas.
  • Hurricanes & Floods - The NIEHS Worker Training Program and its awardees are involved in response to hurricanes and floods as well as cleanup activities after such disasters. Find free safety awareness and training resources for emergency responders, skilled support personnel, homeowners, and business owners.
  • Mold Exposure – The NIEHS Worker Training Program developed a Mold Cleanup and Treatment orientation for workers, volunteers, and homeowners who engage in small-scale mold cleanup and treatment of flooded or water-damaged homes.
  • Vectorborne and Zoonotic Diseases – Vectorborne and zoonotic diseases are infectious diseases whose transmission involves animal hosts or vectors.
  • Waterborne Diseases – Outbreaks of waterborne diseases often occur after a severe precipitation event (rainfall, snowfall).
  • Wildfires – From the NIEHS Worker Training Program, resources and training in support of wildfire response operations in the United States.

Further Reading

Stories from the Environmental Factor (NIEHS newsletter)


  • Wildfire Smoke and Children's Health (2021) – This podcast explores the harmful effects of wildfire smoke on children's health and provides tips to keep kids safe during a wildfire event.
  • Dealing with Disasters (2016) – In Part 1 of this 2-part series, hear about the types of health risks associated with disasters and how disaster research helps to reduce the health-related impacts of disasters. In Part 2, learn what NIEHS is doing to improve researchers' ability to collect data, track recovery, and inform future disaster preparation and response as part of a national disaster risk reduction effort. A Partnerships for Environmental Public Health (PEPH) podcast from January 19, 2016.

Additional Resources

  • Extreme Weather Collection
    This collection from the journal Environmental Health Perspectives presents high-impact research, reviews, feature articles, podcasts, and other materials. Numerous studies have explored the impacts of heat and other weather extremes on human health. By improving our understanding of the risks of weather extremes, scientists and policy makers can develop a strong evidence base for public health planning and disaster response.
    The Federal Emergency Management Agency, an official website of the Department of Homeland Security.
    From the National Hurricane Center, an office of the National Oceanic and Atmospheric Administration.
    Ready is a national public service campaign designed to educate and empower the American people to prepare for, respond to and mitigate emergencies, including natural and man-made disasters.

Related Health Topics

For Educators

  • Climate Change and Human Health Lesson Plans – NIEHS developed learning modules suitable for use in high school and secondary school courses on earth, life, and environmental science, history, geography, health care or social studies classes. The modules challenge students to consider the complex interactions between environmental health and human health and prompts students to take action to improve their communities and design interventions to enhance climate resilience.
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