How Cities Can Make Heat Waves Manageable

Man Drinks From Water Bottle For Relief From Heat

Avoiding Disaster When Extreme Weather Is Inevitable

The past year has seen devastating hurricanes, floods, fires, and other types of extreme weather. But as we transition into the summer months, officials must prepare for the deadliest extreme weather event – heat waves.

Though the weather is inevitable, risks associated with it are not. Even with limited resources, cities can prevent extreme weather from becoming deadly by identifying their most vulnerable and exposed populations, and giving them what they need to make it through.

Vulnerability, Exposure, and Resilience

Reducing health risks from and increasing resilience to extreme weather events depends on three interrelated components: vulnerability, exposure, and resilience. Each component varies by location, ensuring that mapping is critical to risk reduction.

(Vulnerability + Exposure) − Resilience = Risk

Vulnerability refers to the degree to which property, businesses, and, most importantly, people, can be damaged or harmed by disasters or extreme weather. People can be particularly vulnerable to disasters because of preexisting health conditions, because of logistical concerns, such as not having access to vehicles for evacuations, or because of social reasons, such as language barriers. The CDC has developed an index that summarizes some of the most common reasons for people to be vulnerable to disasters. The index can help emergency planners begin to identify neighborhoods where vulnerable populations live.

Exposure refers to being in a location that is likely to be threatened by flooding, fire, or another extreme event. Vulnerable people that don’t have exposure to disasters are not at risk. They are only at risk from a disaster if they are located in a place that may be impacted, such as a coastal community or near a combustible forest. Historic data on disasters can help identify areas that may be affected by similar problems in the future.

To summarize, someone can be vulnerable to heat due to their age, but if they live in Alaska, they’re unlikely to be exposed to it. Someone can be exposed to heat all the time because they live in Arizona, but not be vulnerable because they live in an air-conditioned residence.

Communities that are vulnerable and exposed to disasters can have their risk of harm reduced. Resilience, sometimes referred to as adaptive capacity, refers to the resources that a community can depend on to recover from disaster quickly. Neighborhoods that have vulnerable people and lie within areas that might be impacted by extreme weather may still be at low risk from those events if they have a strong healthcare system, an active network of community organizations, or other resources that can help them prepare and recover.

Preparing for Extreme Heat

Heat waves are the most deadly extreme weather events in the United States, killing more than 600 people each year. Prolonged exposure to high temperatures, particularly when exacerbated by high humidity, can be very taxing on the human body, and can lead to heat stroke.


Older adults, young children, and people with heart or breathing problems are particularly vulnerable. In St. Louis, a city that has suffered a number of heat related deaths in recent decades, the northwestern area of the city contains several tracts with high concentrations of people over the age of 65 who may be in need of extra attention during heat waves.


People who work outside are more likely to be exposed to dangerously hot temperatures. People who live in urban areas with lots of dark pavement or rooftops are also more exposed to dangerous air temperatures than others. These areas of dark pavement often act as “heat islands” that trap high temperatures during the day to release heat over night. This continued exposure to heat during the night can be particularly dangerous, since it doesn’t give the body a chance to recover.

In St. Louis, the same northwestern neighborhood that has concentrated populations of older adults is also lower income. It may be in need of extra cooling centers or networks of people to confirm that elderly adults have access to air conditioning in their homes and have the funds to pay for higher electric bills during hot summer months.

People working in construction would also face greater heat exposure. Again, if they don’t have the ability to recover in a cooled space at the end of the day, they may face elevated risk. Construction workers are prevalent in certain specific neighborhoods in St. Louis. Where they live would be another consideration for public health officials to consider.


After identifying the areas of highest vulnerability, an inventory of current assets helps establish how resilient that neighborhood may be. For example, United Way has published a list of cooling centers for St. Louis, where residents can go during heat emergencies to escape the heat. Overlaying these points onto a map of population by age reveals that some older neighborhoods may be good candidates for opening additional centers during summer months, making the high-vulnerability, high-exposure area more resilient.

Cities already have assets that can be used as cooling centers, like schools and community health centers. (In St. Louis, libraries are already cooling centers.)

Simply opening enough cooling centers is not enough. Residents need to know that they are available, where they are located, and when they are open. Partnering with local schools, community health centers, and non-profits can help public health professionals reach people who are most likely to need those services. The CDC has published guidance on how best to advertise cooling centers, including issuing heat alerts and providing up-to-date information on a website. Mapping language proficiency and internet access can provide some guidance on how people may need to access information in the target neighborhood. Some neighborhoods in St. Louis have lower rates of internet access, for example, so providing information on cooling centers on pamphlets or posters may be warranted.

Recent natural disasters have highlighted the importance of preparation in making sure that people are able to recover from disasters with minimal risks to their health and livelihoods. The last year has seen flooding, hurricanes, fires, and climate change means these events are likely to continue. Municipal staff and public health officials can save lives prepare for these events by knowing their regions’ exposure levels to disaster, knowing where vulnerable populations live, and taking advantage of existing assets to make communities more resilient.

Is your organization working to reduce health risks from and increase resilience to extreme weather events? We can help. Contact us.