SA Heat Maps

The increasing heat is part of the trend of human-caused climate change. The burning of fossil fuels is driving catastrophic changes to global weather patterns and fueling extreme weather events. Locally, we have seen average temperatures steadily increase since 1900, with an acceleration beginning in the 1970s.

Not only was 2023 the hottest summer on record, the 75 days over 100 degrees in 2023 exceeds the City’s climate projection report that predicted 61 days over 100 degrees by mid-21st century. This means we are experiencing the effects of climate change much sooner than projected.

Some parts of San Antonio can get even hotter than others – and certain residents are more vulnerable than others to the rising heat. These inequities are driven not only by socioeconomic conditions, but also the Urban Heat Island effect: higher temperatures in areas with more physical infrastructure such as concrete, asphalt and steel, which absorbs heat during the day and radiates it out at night. Poverty only increases vulnerability to heat for those who can’t afford to turn up the air-conditioning - or may not even have an air conditioner.

The consequences can sicken. Hot days increase ground-level ozone, a pollutant that can worsen respiratory illness. Extreme heat can cause dehydration, heat cramps, heat exhaustion, heat stroke and even death. In fact, heat is the deadliest weather-related hazard in the United States. The risk increases for those who work outside, live alone, can’t access a cooler location, and suffer from pre-existing conditions. Infants and older residents are also at higher risk.

As seen in the graph, heat-related illnesses are rising as our summers in San Antonio grow hotter. The highest numbers of heat-related illnesses were reported in 2022 and 2023 – our hottest summers on record.

The City of San Antonio wants to help – and use data to do it. This year, the City partnered with the University of Texas at San Antonio's Sustainable Pervasive Urban Resilience  (SPUR) Center  to help direct resources toward the areas most impacted by extreme heat. UTSA faculty used the  Landsat  program operated by the USGS and NASA to measure relative heat, then combined this data with other factors, such as income and race, to determine urban heat vulnerability across the city.

Explore the interactive map to see how vulnerable your neighborhood is to extreme heat. The Heat Vulnerability Score combines the heat, income, and race scores. Click on the circle at left to see a legend for Heat Vulnerability Score. Higher scores indicate more vulnerability. Click on the map or use the Zoom buttons at right to zoom in and out. Click on the Home button to refresh the map or the target button to search near your location.

In 2023, the City’s Office of Sustainability commissioned UTSA’s Sustainable, Pervasive Urban Resilience  (SPUR) Center  to assess urban heat vulnerability in San Antonio. The study was funded by the City’s Office of Innovation Research and Development. It was performed by Kristen E. Brown, PhD; Esteban Lopez Ochoa, PhD; Ryan Jun Lee, PhD; and Wei Zhai, PhD, with assistance from Samuel Rueda, Allison Pineda and Christina Kastely, graduate students in the Klesse College of Engineering and Integrated Design at UTSA.

Read the entire study here:  An Assessment of Urban Heat Vulnerability in San Antonio, TX  

Explore the interactive maps to compare the heat rank and equity scores. Click on the circle at left to see a legend for Heat and Equity scores. Higher heat rank scores indicate higher land surface temperatures. Higher equity scores indicate social inequality represented by communities with more people of color and lower income levels. Click on the map or use the Zoom buttons at right to zoom in and out. Drag the vertical line to see more or less of temperature or social vulnerability. Click on the Home button to refresh the map.

The City will use this data to inform its ongoing Heat Response Strategy, which already incorporates a range of programs and policies to address urban heat.

Among them, the City offers cooling relief during the day at city facilities such as libraries, senior centers, and swimming pools. Explore the map to find some relief near you.

The  City’s Under One Roof (U1R) program  replaces dark shingles with lighter ones to better reflect heat, making homes cooler and reducing the Urban Heat Island effect.

In 2021, San Antonio became the first City in Texas to use Cool Pavement, a water-based asphalt treatment that reflects more sunlight and absorbs less heat. The City expanded its initiative in 2023, applying  Cool Pavement  products to sections of roadway in all 10 Council Districts and partnering with UTSA to study the locations for their potential to cool the city down. Explore the interactive map to see all project sites.

The pilot program tested the effectiveness of three separate cool pavement treatments. The study assessed surface temperature, air temperature and wet bulb globe temperature (heat plus humidity), among other measures. SealMaster showed the most consistent and significant reduction in surface temps with an average reduction of 3.58 degrees. The maximum surface temperature reduction relative to fresh asphalt was 18°F. The findings showed a “clear potential” for cool pavement to reduce surface temperatures.

Read the entire study here:  Evaluating the Urban Heat Mitigation Potential of the San Antonio Cool Pavement Pilot Program  and  Evaluation of Cool Pavement Surface Treatments Using Friction, Texture and Adhesion Properties