Extreme Heat in San Antonio
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Extreme Heat in San Antonio
Warmer Nights
As our climate continues to change, San Antonio can expect more nights where temperatures stay above 80°F. Higher humidity traps heat after the sun goes down, preventing the city from cooling off as it once did. At our current pace, nights over 80 degrees could become the norm rather than a rare event.
Data from Climate Central shows that climate change has led to more warmer-than-normal summer nights in 246 major U.S. cities since 1970. In San Antonio, average nighttime summer temperatures have increased by about 3 degrees over that time.
Warmer nights make it harder for people to recover from the heat of the day—especially for our most vulnerable residents. Homes and buildings must rely on air conditioning for longer periods overnight, increasing energy use and placing added strain on our power system. As a result, there are fewer opportunities to cool down, even after sunset.
Extreme Heat in San Antonio
Heat and Air Quality
San Antonio has made significant progress in improving local air quality, particularly by reducing ground-level ozone. Ground-level ozone is both an air pollutant and a greenhouse gas that can irritate the lungs and airways, trigger asthma attacks, and make it harder to breathe—especially for children, older adults, and people with respiratory conditions. Ground-level ozone becomes more difficult to control as extreme heat creates conditions that allow ozone to form and linger. As the number of very hot days increases, managing ozone pollution will become more difficult, challenging the progress that the City has managed to make so far.
Using EPA data, Climate Central analyzed days when ozone levels reached unhealthy levels in 244 U.S. cities and identified 54 cities where ozone is a recurring issue—including San Antonio. The analysis shows that San Antonio is now experiencing a longer ozone exposure season, lasting approximately 9 to 10 months each year.
Extreme Heat in San Antonio
Heat-Related Illness
The San Antonio Metropolitan Health District tracks emerging public health challenges related to extreme heat, including cases of heat exhaustion, dehydration, heat stroke, and heat-related deaths. While these incidents remain relatively uncommon today, they provide important early warning signs as temperatures continue to rise.
The City of San Antonio is actively working to keep heat-related illness (HRI) rates low through ongoing monitoring, prevention, and coordination across departments. The Department of Resilience and Sustainability will continue to monitor this data and work closely with the Metropolitan Health District to identify trends, support early interventions, and strengthen community preparedness, helping to build resilience and protect public health as extreme heat becomes more frequent.
Explore 2025 HRI data through the Bexar County Heat-Related Illness Dashboard below: