Skip directly to search Skip directly to A to Z list Skip directly to navigation Skip directly to page options Skip directly to site content

About CDC's Program

What is the public health problem?

Exposure to excessive heat can cause illness, injury and death. Approximately 400 people die each year from exposure to heat due to weather conditions, and many more people die from health conditions that are exacerbated by exposure to excess heat. Most heat-related deaths occur during the summer months. The elderly, the very young, and people with chronic health problems are most at risk. Air conditioning is the leading protective factor against heat-related illness and death. By knowing who is at risk and what prevention measures to take, heat-related illness can be prevented.

What has CDC accomplished?

  • In 1980, 1995, and 1999, CDC staff members conducted case-control studies in Midwestern cities to identify risk factors associated with heat-related deaths and deaths due to cardiovascular causes during heat waves.
  • In 2000, CDC staff members assessed the city of Chicago’s “Extreme Weather Operations Plan” and evaluated its impact on mortality during the 1999 heat wave.
  • CDC staff members published an evaluation of heat emergency response plans [1]  for 12 cities.
  • Each year, CDC publishes an update of heat-related mortality in the United States in CDC’s Mortality and Morbidity Weekly Report.
  • CDC works on guidelines to assist state and local health departments in their development of city-specific comprehensive heat emergency response plans.

What are the next steps?

CDC will (1) continue to collaborate with public health authorities nationally and internationally to communicate the risks of extreme heat; (2) further evaluate current heat emergency response plans with emphasis on their ability to predict mortality and morbidity associated with specific climatologic factors and their public health effect and; (3) assume a leadership role in evaluating heat emergency response plans in order to identify plan components that can be adopted by city health departments.

This information provided by NCEH's Health Studies Branch.


1. Bernard S.M., McGeehin M.A. Municipal heat wave response plans. Am J Public Health 94:1520-1522.

Extreme heat infographic badge.