Hot summer city temperatures have serious health impacts, including heat stress during heat waves, and dangerous ground-level ozone levels on the hottest days of the year. Higher summer temperatures also stress the electricity grid as air conditioner use soars.
The roads, buildings, and infrastructure in urban areas make cities much hotter than rural areas, which often have more plants and trees. 57 of the 60 cities analyzed had measurable urban heat islands over the past 10 years. In the summer, temperatures can be as much as 15-27°F hotter in cities.
Summers in the city have been getting hotter, faster than in rural areas since 1970, as exemplified in 45 out of the 60 cities we analyzed. Hotter temperatures and urbanization are increasing risks for the 80% of Americans living in cities.