What is already known about this topic?

Exposure to excessive heat is an increasing threat in a warming climate. Some groups, including older adults, are disproportionately affected by heat exposure.

What is added by this report?

Heat exposure and heat-related illness (HRI) increased in Maricopa and Yuma counties, Arizona, during 2010–2020. Heat-related hospitalizations were higher among adults aged ≥65 years than those aged <65 years. Barriers to cooling center access among older adults include awareness of location and transportation.

What are the implications for public health practice?

States and communities can implement adaptation and evaluation strategies to mitigate and assess heat risk, such as the use of cooling centers to protect communities disproportionately affected by HRI during periods of high temperatures.