Understanding Nashville Heat

This website is intended to serve as a tool to educate Nashvillians on the concept of extreme heat. In the following sections, you will learn about heat in our city, why some parts of the city are warmer than others, who is most vulnerable, which neighborhoods are most exposed, and actions you can take to protect yourself and your community from extreme heat events.

Extreme heat, also referred to as "heat waves", is defined as a period of high heat and humidity with temperatures above 90°F for at least 2 to 3 days. Extreme heat is the leading cause of death among all hazardous weather events and produces more premature deaths than all other hazardous weather events, COMBINED.

In Nashville, climate change is predicted to worsen extreme heat more than any other weather threat. While temperatures are expected to rise by a minimum of 1.5°C worldwide (IPCC, 2018), this represents a global average and hides the fact that extreme heat events will increase in frequency, duration, and intensity (IPCC, 2021).

According to a peer-reviewed report by First Street Foundation, Davidson County is expected to have 26 extreme heat days in 2023.  By 2053, this number is expected to rise to 45  (First Street Foundation).

The effects of extreme heat include detrimental public health outcomes as well as infrastructural and economic challenges

In the Summer of 2022, local experts, nonprofits, and researchers teamed up with community scientists to measure temperatures and humidity across Nashville and Davidson County during a one-day heat mapping campaign. This data revealed the warmest and coolest neighborhoods in the city and is being used to help inform heat mitigation efforts by city public health and environmental officials, nonprofits, urban planners, urban foresters, and researchers.

For more information on the 2022 Metro Urban Heat Mapping Campaign, click the button below.

The following maps show the results of the Nashville Heat Mapping Campaign. Due to Nashville's humid climate, it is important to understand which parts of Nashville become the hottest during high-humidity days. Humidity contributes to something called the 'Wet Bulb' temperature, an indicator of heat-related stress on the human body. At high Wet Bulb temperatures (>95 °F), the body is unable to cool itself through sweat, which can lead to organ failure and even death in the absence of artificial cooling (National Oceanic & Atmospheric Administration.

While Wet Bulb temperatures also account for wind speed, sun angle, and cloud cover, the heat index as an indicator of combined temperature and humidity is a more accurate representation of heat exposure than temperatures alone. In Nashville, the highest heat indices, an indicator of humidity, do not align with the highest temperatures...

According to the Intergovernmental Panel on Climate Change (2021), global average temperatures have already risen 1.0°C above pre-industrial levels. However small this may seem, this means that Nashville and other cities around the globe will experience both more extreme heat events and extreme heat events of greater severity.

Air temperatures in urban environments are even greater than in surrounding areas due to the absorption of heat during the day from dark or "low-albedo" surfaces. This is known as the Urban Heat Island Effect. Roads, parking lots, and buildings effectively absorb heat from the sun and continue to release it throughout the day, especially at night. These features, as well as others such as vegetation and shade that help to cool the environment, are unevenly distributed across cities, including Nashville. This leads to some neighborhoods being hotter than others and increased risk for some residents relative to others.

Many other factors may affect ambient air temperatures or the temperature that residents actually feel, including building height, density, proximity to water, and wind direction. The image below provides a useful representation of the relationship between land cover and temperatures.

Across the nation, people of color are disproportionately exposed to the Urban Heat Island effect compared to non-Hispanic whites (Hsu et al., 2021). This may be due to the effects of historical urban planning processes such as redlining, state highway construction, and urban renewal on the presence of vegetation and impervious surfaces in minority neighborhoods (Hoffman et al., 2021; Jesdale et al., 2013; Wilson, 2020).

In Nashville, formerly redlined, historically Black neighborhoods such as North Nashville, Edgehill, and parts of East Nashville were targeted for interstate highway construction and industrial uses, and experienced disinvestment as a result of federal urban renewal and Model Cities programs (Doyle, 1985; Mohl, 2014; Erickson, 2016). This led to an increase in heat-storing infrastructure and other environmental hazards such as air pollution from increased vehicle traffic in these neighborhoods. While recent development and gentrification have changed the physical and demographic makeup of these areas, this history highlights the importance of considering environmental justice and equity in Nashville's plans to become a more resilient city.

Vulnerability to heat is not entirely determined by exposure, or the temperature of the places you live, travel, work, and recreate. Vulnerability is also determined by a person's sensitivity to heat and access to resources during extreme heat events.

According to the CDC, older adults, young children, and people with mental illness and chronic diseases are at the highest risk. Other factors that may affect an individual's risk of developing heat stroke or related conditions include:

Housing/Living Conditions:

• People who live outdoors
• People without central AC
• People living alone
• People living in poorly constructed housing units

Individual Sensitivities that may affect Thermoregulation (the capacity to cool the body)

• People with chronic illnesses
• Being overweight
• Being pregnant
• Older adults
• Young children

Factors that Limit Access to Resources:

• People with disabilities
• Low-income individuals or households
• Individuals without access to reliable transportation
• Non-English speakers

Other Factors

• Outdoor workers
• Other essential workers who may not be able to stay home on extremely hot days
• Athletes and outdoor recreators

The following conditions affect the body's ability to cool itself during extreme heat events or are exacerbated by extreme heat:

• Asthma
• Diabetes
• Obesity
• Coronary Heart Disease
• Chronic Obstructive Pulmonary Disease (COPD)

Heat risk is determined by many factors. Exposure to heat, or the degree to which one experiences very hot temperatures due to where they live, work, and play, is an obvious threat. Sensitivity to heat is determined by the body's ability to cool itself when exposed to high temperatures and is determined by age, overall health, and chronic conditions. Finally, there are factors that may limit a resident's ability to access resources such as physical isolation (living alone, not having reliable transportation, etc...), linguistic isolation, or having a lower income.

All of these factors are unevenly distributed across Nashville's Neighborhoods. The following maps show where Nashvillians are most vulnerable.

While heat poses dangers to public health, there are many actions individuals and organizations can take to protect themselves and their communities. Read on to find out more...

Prepare for Extreme Heat...

• Learn to recognize the  signs of heat illness 
• Know where the closest Cooling Center or other public space with AC is in case of a power outage
• Do not rely on fans as a primary cooling device
• Cover windows with drapes or shades

For more information on how to stay informed of extreme heat events and other hazardous weather events, please visit the Office of Emergency Management's (OEM) information page:

During Extreme Heat Events...

• Watch for signs of heat illness
• Never leave people or pets in a closed car
• Wear loose, lightweight, light-colored clothing
• Use your oven less to reduce the temperature in your home
• If you're outside, find shade. Wear a hat wide enough to protect your face
• Stay hydrated by drinking plenty of water or other fluids
• Avoid high-energy activities or work outdoors during peak hours (10:00am - 7:00pm)
• Consider pet safety. Make sure they have plenty of water and access to shade. Asphalt and dark pavement can be very hot on your pet's feet.
• If your power goes out or you do not have access to AC, seek relief at a Cooling Center.
• Take cool showers or baths
• Check on family members, seniors, and neighbors (especially those living alone or with chronic health conditions or disabilities)

For more information on protecting yourself during extreme heat events, please visit the Office of Emergency Management's information (OEM) page:

New Construction

• Install reflective materials, cool roofs, or green roofs to cool neighborhoods
• Focus on efficient heating and cooling systems such as heat pumps to reduce energy consumption and heat production
• Passive cooling methods such as improved insulation, reflective walls, and less glass reduce the amount of heat trapped within a building

Existing Buildings

• Install reflective roof coatings
• Increase airtightness, insulation, and weatherization
• Upgrade heating and cooling systems to reduce waste heat emissions

The Elderly, families with young children, and disabled residents with medical conditions affected be extreme heat conditions may be eligible for a free fan and/or air conditioning unit. Click the button below for more details.

Limited income homeowners may also be eligible for free home energy upgrades & renovations through the Home Uplift program. Click the button below to find out how to apply.

Site-level Recommendations

• Installation of stormwater infrastructure such as bioswales and rain gardens
• Use cool pavement or otherwise minimize the surface area of impermeable surfaces
• Plant native species that are more heat and drought tolerant

To learn more about free trees for Neighborhood Yards through the Root Nashville Campaign and the Cumberland River Compact, click the button below.

For more information on actions the development community can take to mitigate extreme heat, see the Urban Land Institute's report on Heat Resilience and Equity in Nashville.

To protect your employees...

• Provide care and resources to your employees that might be exposed to heat while working, such as providing shade, water, and minimizing outdoor work during the hottest hours of the day (Keep Cool DC)

To protect your customers or constituents...

• Use your space to offer residents a break from the heat (Keep Cool DC)
• Advocate for or install shade near your place of work (Keep Cool DC)

To learn more about free trees for private properties through the Root Nashville Campaign and the Cumberland River Compact, click the button below.

In the Summer of 2023, community partners including local universities, non-profit organizations, and other community organizations will be collecting community narratives on the lived experiences of heat. These narratives will be incorporated into this StoryMap to deepen collective understanding of the barriers faced and strategies for keeping cool on extreme heat days and will inform protective interventions.

The results of the survey below will also be incorporated into this StoryMap to show Nashvillians how their neighbors relate to and behave during extreme heat events.

Since heat is an interdisciplinary issue, many Metro departments have a hand in 1) reducing air temperatures and heat exposure and 2) providing services to residents during and before extreme heat events to minimize adverse outcomes for Nashvillians.

The following section highlights some of this important work.