June 1 is the first day of meteorological summer!
Since 1970, 96% (235) of 246 U.S. locations had an increase in their summer average temperature and 81% (200) had 7 or more summer days above normal since 1970.
Over the last 52 years, summer warming was greatest in the western and southwestern U.S.
Hotter summers can lead to heat-related illness and exacerbate poor air quality. Vulnerable populations like children, athletes, low-income households, outdoor workers, and people with chronic illnesses are most at risk.
June 1 is the first day of meteorological summer. This year’s summer package includes:
Trends since 1970 in: summer average temperature and days above normal for 246 U.S. locations
A national map of the change in summer temperatures since 1970
The heat is on. As planet-warming gases from fossil-fuel burning increase global average temperatures, we’re experiencing more extreme heat events. Extreme heat is most apparent in the summer since it's the hottest time of year.
52 years of summer warming. A Climate Central looked at 52 years (1970-2021) of summer temperature data in 246 U.S. locations, and found that:
Average summer temperatures are rising. 96% (235) of the locations analyzed had an increase in average summer temperature. 53% (126 of 235) of those locations warmed by 2°F or more.
Summer warming was greatest in the western and southwestern U.S. The three greatest increases in summer average temperatures since 1970 were in Reno, Nev. (10.9°F), Las Vegas, Nev. (5.8°F), and Boise, Idaho (5.6°F).
More summer days above normal. Since 1970, 81% (200) of locations had 7 or more days above their 1991-2020 summer normal temperature. And 37 locations had 30 or more summer days above normal.
Extreme heat is a serious health hazard. Exposure to extreme heat makes it difficult for our bodies to cool off, resulting in heat-related illnesses including heat cramps, heat exhaustion, and potentially fatal medical emergencies like heat stroke.
Summer heat can also exacerbate poor air quality by trapping harmful pollutants close to the Earth’s surface and creating ground-level ozone. These pollutants can exacerbate respiratory issues in people with asthma and other lung diseases.
From 1979 to 2018, more than 11,000 Americans died from heat-related illness. In a recent study, researchers concluded that heat-related deaths in the U.S. may be “substantially larger than previously reported.”
According to The Centers for Disease Control and Prevention, the most vulnerable populations to excessive heat areinfants and children, athletes, adults over 65, outdoor workers, low income households, and people with chronic medical conditions.
POTENTIAL LOCAL STORY ANGLES
How does heat impact cities? Which neighborhoods are most susceptible to excessive heat?
Climate Central’s urban heat island report analyzed heat island intensity in 159 U.S. cities. The Future Heat and Vulnerability Map created by the National Integrated Heat Health Information System (NIHHIS) assigns a vulnerability score to each county across the U.S. based on race, income, and other parameters.
What measures are local officials taking to protect people from extreme heat?
The EPA maintains a Community Actions Database of measures that communities are taking to mitigate the heat island effect in their area. Emergency management can help reduce climate risk in vulnerable communities. FEMA has a dedicated page with tools, data, and resources on climate resilience. For state-specific emergency management information, search for your state on the USA.gov site.
What is being done to protect vulnerable populations?
Check out resources like the EPA guidebook for excessive-heat response, vulnerability-focused stories and projects from ISeeChange, and risk management strategies from the National Integrated Heat Health Information System.
The SciLine service, 500 Women Scientists or the press offices of local universities may be able to connect you with local scientists who have expertise on extreme heat and warming summers. The American Association of State Climatologists is a professional scientific organization composed of all state climatologists.
Melissa Guardaro, Ph.D.
Assistant Research Professor, School of Sustainability
Arizona State University
Topics: extreme heat, urban heat islands
Juan Declet-Barrero, Ph.D.
Senior Social Scientist, Climate Vulnerability
Union of Concerned Scientists
Media Contact: Ashley Siefert Nunes, Climate Communications Officer firstname.lastname@example.org
Topics: climate vulnerability
*Interviews available in both Spanish and English
Vijay Limaye, Ph.D.
Senior Scientist, Climate & Health
Natural Resources Defense Council
Media Contact: Jake Thompson, Senior Press Secretary email@example.com
Topic: public burdens of air pollution and extreme heat, economic valuation of climate-related health problems
Summer (June, July, and August) temperature data from 1970-2021 were obtained from the Applied Climate Information System. Displayed trend lines are based on a mathematical linear regression. Climate Central's local analyses include 247 stations. However, for data summaries based on linear trends, only 246 stations are included due to large data gaps in Wheeling, W. Va.