The U.S. Environmental Protection Agency provides information on the heat island effect, its impacts, and the strategies that communities can take to reduce urban temperatures here: Heat Island Effect | U.S. EPA
Hotter temperatures increase the rate of ground-level ozone formation – air pollution that worsens in Austin’s April – October “Ozone Season.”
During summer months, higher temperatures and associated air pollution can cause discomfort, respiratory difficulties, heat cramps and exhaustion, heat stroke, and even heat-related deaths, particularly in sensitive populations such as children, older adults, and those with existing heart conditions.
Hot pavement and rooftop surface temperatures heat stormwater runoff, which raises water temperatures in creeks, rivers, and lakes and can be stressful, even fatal, to aquatic life.
Hot weather drives up demand electricity used for cooling, which leads to an increase in emissions from power plants – both air pollutants and greenhouse gases.
Did you know? On warm summer days, surface temperatures in urban areas can be as much as 22° warmer than actual ambient air temperatures. Dark roofs and impervious surfaces such as pavements can be as much as 50–90° hotter than shaded surfaces.