Heat & Heat-related Illness

At a glance

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 ways, some of them severe.

We Track That

The Tracking Program partners with CDC's Climate and Health Program to host data on extreme heat and its health effects. These data can be used to track the effects of climate change and help communities respond. Knowing how to prepare for and respond to extreme heat events will help protect our communities, especially the most vulnerable populations.

Get local heat and health data resources.‎

The CDC Heat & Health Tracker provides local heat and health information so communities can better prepare for and respond to extreme heat events.

Types of Data

The Tracking Network provides the following data to better understand extreme heat and its health effects over time. The data come from several sources.

Temperature and Heat Projections

This heat indicator uses modeled county-level data to show projections of extreme daytime and nighttime temperatures. Use these data 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 historical heat indicator shows temperature, heat index, and number of days to define extremely hot days and extreme heat events. It uses modeled data by county and census tract during May-September of each year.

Heat-related Emergency Department (ED) Visits

This ED visits 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.A B

Heat-related Hospitalizations

This hospitalizations 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.A B

Heat-related Mortality

This mortality indicator is based on data from death certificates in which heat has been identified as an underlying or contributing cause.

Heat Vulnerability & Preparedness

This indicator includes measures that may make people at greater risk for heat-related health effects. These measures include personal health issues, socioeconomics, and environmental factors.

Access the Data

Use the Data Explorer to create custom maps, tables, and charts.

View data in simple Quick Reports.

Get machine-readable data through the Application Program Interface (API).

Data in Action

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

  • Identifying conditions that make people vulnerable during extreme weather events
  • 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 specific populations

Resources & Tools

Heat & Health Tracker

  1. 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.
  2. These data are supplied by health departments funded by the CDC Tracking Program.