Heat & Heat-related Illness

Man wiping his brow suffering from heat stress illness

As a result of the changing climate, serious weather events, like heat waves, happen more often. These changes have the potential to affect human health in several direct and indirect ways, some of them severe.

We Track That

We partner with the Climate and Health Program to host data from several sources to track the effects of climate change and help communities respond. The Tracking Network also collects data on heat-related illnesses throughout the United States and provides information so people can protect themselves. Knowing how to prepare for and respond to extreme heat events will help protect our communities, especially the most vulnerable populations.

Types of Data

The Tracking Network provides data about extreme heat, heat-related health effects, and the vulnerabilities that increase risk for health effects related to those events.

Extreme Heat

  • Temperature and Heat Projections
    This indicator allows you to use modeled county-level data to look at projections of extreme daytime and nighttime temperatures to better understand how our climate is changing. These data can be used to understand trends in heat over time and focus preparedness plans to lessen the health effects of extreme heat.
  • Historical Temperature and Heat Index
    This indicator allows you to look at temperature, heat index, and number of days to define extremely hot days and extreme heat events using modeled data by county and census tract during May-
    September of each year.

Heat-related Illness

  • Heat -related Emergency Department Visits * ¶
    This indicator estimates the number and rate of emergency department visits for heat stress. It includes all cases where heat stress is listed as a primary or other diagnosis.
  • Heat -related Hospitalizations * ¶
    This indicator estimates the number and rate of hospitalizations for heat stress. It includes all cases where heat stress is listed as a primary or other diagnosis.
  • Heat-related Mortality
    This indicator is based on data from death certificates to evaluate deaths that have identified heat as an underlying or contributing cause.

Heat Vulnerability & Preparedness

  • Heat Vulnerability & Preparedness
    This indicator includes measures that may make people at greater risk for heat-related health effects. These measures are diabetes, heart disease, poverty, race, advanced age, social isolation, disabilities, population density, forest canopy, developed land use, and cultivated crop land use.

* These data come from hospital records and may not capture the full range of heat-related illness if exposure to excess heat is not explicitly documented. These data can be used to document changes over place and time, monitor vulnerable areas, and evaluate the results of local climate-adaptation strategies.
¶ These data are supplied by health departments funded by the CDC Tracking Program.

Data Highlight
CDC's Climate & Health Heat Tracker tool screenshot

CDC’s Heat and Health Tracker:
Explore how extreme heat affects your county, populations that are at risk, and resources for response.

Data in Action

Reviewing these national data helps scientists make comparisons between environmental conditions and health problems. Specifically, uses of extreme heat data include:

  • Identifying conditions that make people vulnerable during extreme weather events
  • Better understanding the possible health effects and risks to specific groups of people, particularly for heat-associated death
  • Evaluating extreme weather events at the national level, while allowing for comparisons across states
  • Gaining a better understanding of trends in heat-related illness and deaths over time
  • Comparing health trends among states and counties to plan interventions
  • Designing interventions and communication efforts for at-risk populations.

Read these success stories to learn about the heat stress illness related work happening in our funded Tracking Programs.

California | Minnesota | Missouri | New Hampshire | New York City

Learn More

Tracking Resources

Explore Heat & Heat-related Illness Data
Data Explorer
screenshot of Tracking Network data explorer tool

Create custom data visualizations, save, & share results

Quick Reports
Asthma Quick Reports web page screenshot

View data in simple charts

API graphic text

Access machine-readable data

Page last reviewed: October 21, 2020