Climate MattersMay 21, 2024

2024 Summer Package


  • Meteorological summer starts June 1, and the season is heating up across the U.S. 

  • Since 1970, summers have warmed in 230 U.S. locations — by 2.5°F on average.

  • More than half (58% or 139) of all locations analyzed now experience at least two more weeks worth of unusually hot summer days than in 1970. 

  • On average, summer is heating up most across the Northwest, Southwest, and South.

  • Hotter summers lead to heat-related illness and worsen air quality — putting health at risk.

  • Find reporting resources for summer heat and Atlantic hurricane season (June 1 - November 30).

The Atlantic hurricane season also begins on June 1

A few reporting resources for the season: 

Official outlook: NOAA will issue their 2024 Atlantic hurricane season outlook on Thursday, May 23. Credentialed reporters can register to attend the news conference that morning. 

Real-time updates: Check for updates about active tropical weather systems throughout the season.

Early outlook: Colorado State University’s 2024 Atlantic seasonal hurricane forecast, released in early April and available in English and Spanish, anticipates an extremely active season.

Hurricane safety: NOAA’s Hurricane Preparedness hub provides safety information and resources to help communities stay safe before, during, and after hurricanes.

New Spanish products: The National Hurricane Center will issue Spanish text products such as advisories and tropical discussions for the first time this upcoming season. Check the National Hurricane Center Products and Services Update for 2024 Hurricane Season for details. 

Climate change and hurricanes: Check out Climate Central’s Extreme Weather Toolkit: Tropical Cyclones for quick facts and a collection of reporting resources on hurricanes and climate change. 

The heat is on

The planet’s record heat streak, which began in June 2023, has continued well into 2024. April 2024 marked 11 consecutive months of record-breaking global temperatures. NOAA’s latest projections gave 2024 a 61% chance of beating 2023 as the warmest year on record. 

Summer 2023 was Earth’s hottest on record (since 1850) and likely the hottest in the last 2,000 years. During that record-breaking summer, 326 million people in the U.S. — 97% of the population — experienced at least one day of heat made at least two times more likely due to human-caused climate change.

As the planet’s heat streak continues, summer 2024 is likely to be hotter than normal across much of the U.S., from the Northwest down through the Southwest and into Texas, as well as across the Northeast.

As continued carbon pollution traps more heat in Earth’s atmosphere, summer temperatures are arriving earlier and getting hotter — and risky heat extremes are becoming more frequent and intense. 

Summer temperatures already arrived by May this year from British Columbia in the north to Florida in the south, where temperatures reached Climate Shift Index levels of 2 to 5 — indicating that human-caused climate change made this excessive early-season heat two to five times more likely.

CM: Average Summer Temperatures Map 2024 (EN)
Click the downloadable graphic: Average Summer Temperatures Map

Summer warming since 1970

To understand how the summer season has changed locally as the planet has warmed, Climate Central analyzed the last 54 years (1970–2023) of summer (June, July, and August) average temperature data in 241 U.S. locations (see Methodology).

CM: Average Summer Temperatures 2024 (EN)
Click the downloadable graphic: Average Summer Temperatures

Summers are getting hotter in 230 U.S. cities. 

  • Since 1970, average summer temperatures have increased in 230 (95%) of the locations analyzed. 

  • Summers warmed by 2.5°F on average across these 230 locations. 

  • Nearly one-third (70) of these locations warmed by 3°F or more since 1970.

  • The top five summer warming locations were: Reno, Nev. (11.1°F); Boise, Idaho (6.0°F); El Paso, Texas (5.8°F); Las Vegas, Nev. (5.6°F); and Salt Lake City, Utah (5.6°F). 

Summers are heating up in every region — especially in the western and southern U.S.

  • Every climate division across the contiguous U.S. has experienced summer heating. 

  • Several regions experienced levels of summer warming above the national average of 2.6°F: the Northwest (3.2°F), Southwest (3.2°F), and South (2.8°F). 

CM: Summer Days Above Normal 2024 (EN)
Click the downloadable graphic: Summer Days Above Normal

Unusually hot summer days now happen more often. 

  • Since 1970, 230 (95%) of the locations analyzed have seen an increase in the annual number of days above their 1991–2020 summer normal temperature. 

  • More than half of all locations analyzed (139, or 58%) now experience at least 14 more days of above-normal summer days than in 1970. 

  • And 46 locations now experience 30 or more summer days above normal. 

  • The top 13 locations — with between 45 and 67 more summer days above normal — were in Nevada (Reno); Texas (Houston, McAllen, Austin, El Paso, Bryan, and Odessa); Georgia (Albany); New Mexico (Las Cruces); Louisiana (New Orleans); and Florida (Sarasota, Panama City, and Tallahassee).

Extreme heat is a serious health hazard

More frequent extreme heat is not only an indicator of climate change — it’s also one of the most serious health risks in our warming climate. 

Excessive heat is the leading cause of weather-related deaths in the U.S. Climate change is making spells of deadly heat longer and more frequent. 

Exposure to extreme heat makes it difficult for our bodies to cool off, resulting in heat-related illnesses including heat cramps, heat exhaustion, and even fatal medical emergencies such as heat stroke. 

Summer heat can also worsen air quality by trapping harmful pollutants close to the Earth’s surface. These pollutants can exacerbate respiratory health issues in people with asthma and other lung diseases. 

And as our climate warms, risky heat arrives earlier and lingers later. A recent Climate Central analysis found that 232 U.S. locations have seen the year-round frequency of risky heat days increase — by 21 more days on average since 1970.

Heat risks unequally shared

Extreme heat can affect everyone, but some face greater risks of heat-related illness and mortality than others.

Children, adults over 65, pregnant people, and people living with illness are among those most at risk to heat-related illness. Outdoor workers and athletes also face elevated risk due to work- and recreation-related exposure to extreme heat. 

Structural inequities can also lead to higher extreme heat exposure in some communities. According to a recent study, people of color and people living below the poverty line are disproportionately exposed to urban heat island intensity in 169 of the largest U.S. cities.

Check out Urban Heat Hot Spots to see where heat is most concentrated in your city. 


Is climate change influencing daily heat extremes in your local area?

Climate Central’s Climate Shift Index system provides tools, data, custom maps, and local alerts to answer this question in real-time. Here are three ways to use the Climate Shift Index this summer:

  1. Use the tools. Climate Central’s Climate Shift Index map tool shows which parts of the world are experiencing high Climate Shift Index levels, every day. Explore the global Climate Shift Index map for today, tomorrow, and any day in the recent past.

  2. Access KML to create custom Climate Shift Index maps. The Climate Shift Index is now available in KML format. Fill out this form to join our pilot project, receive the KML links, and create custom Climate Shift Index maps. 

  3. Sign up for alerts. Sign up here to receive custom email alerts when strong Climate Shift Index levels are detected in your local area.

How is extreme heat affecting public health in your local area?

Check out HeatRisk, an interactive map tool from the National Weather Service now available for the contiguous U.S. This color-numeric index shows current and forecast risk of daily local heat-related impacts. HeatRisk is unique because it takes into consideration: how unusual the heat is for the location and time of the year; heat duration (including both daytime and nighttime temperatures); whether those temperatures pose an elevated risk for local communities based on data from the Centers for Disease Control and Prevention (CDC). Additionally, the CDC’s Heat and Health Tracker maps heat-related illnesses at the census tract level in real time. Use the National Integrated Heat Health Information System (NIHHIS) Heat Equity Mapper to explore the burden of extreme heat at the census tract level. Check the U.S. Department of Health and Human Services monthly Climate and Health Outlook for extreme heat outlooks in your region throughout the summer.  

How is the 11-month (and counting) global heat streak progressing?

Climate Pulse, a new tool from Copernicus Climate Change Service makes it easier to monitor and interact with global temperature data in near real-time. Bookmark and check the tool for daily updates to charts and maps of global surface air temperature and sea surface temperature.

What local measures are in place to protect people from heat?

The EPA maintains a Heat Island Community Actions Database of measures that communities are taking to mitigate local heat island effects. Reports from NOAA’s urban heat island mapping campaigns cover local risk reduction and adaptation strategies in 60+ U.S. cities. Track local climate-related hazards in real-time in the Climate Mapping for Resilience and Adaptation Portal, which also includes federal resources for long-term resilience planning. The NIHHIS provides heat preparedness and planning resources, including many resources in Spanish. 


Submit a request to SciLine from the American Association for the Advancement of Science or to the Climate Data Concierge from Columbia University. These free services rapidly connect journalists to relevant scientific experts. 

Browse maps of climate experts and services at regional NOAA, USDA, and Department of the Interior offices.  

Explore databases such as 500 Women Scientists, BIPOC Climate and Energy Justice PhDs, and Diverse Sources to find and amplify diverse expert voices. 

Reach out to your State Climate Office or the nearest Land-Grant University to connect with scientists, educators, and extension staff in your local area. 


Summer (June, July, and August) temperature data from 1970–2023 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. Data summaries based on linear trends include only 241 stations due to large data gaps in the following six: Bend, Ore.; Dothan, Ala.; Hazard, Ky.; Jefferson City, Mo.; Twin Falls, Idaho; and Wheeling, W.Va.

Average summer temperature data for climate divisions in the contiguous United States were obtained via NOAA/NCEI’s Climate at a Glance.