Climate Matters•July 23, 2024
More Extremely Hot Days for School Sports
KEY CONCEPTS
As millions of student athletes begin outdoor practice this late summer, they’re playing in a warmer world than their parents or coaches experienced decades earlier.
Extremely hot days have become more frequent since 1970 in 212 (88% of 242) U.S. locations analyzed by Climate Central.
Most of the locations analyzed (172, or 71%) now experience at least one additional week’s worth of extremely hot days than in the early 1970s.
Exercising and playing sports outdoors during extreme heat is risky for athletes of all ages and experience levels — from Olympians to student athletes.
Preparing for and adapting to more frequent extreme heat is key to protecting the health and safety of athletes in our warming climate.
Download local data
Extreme heat is risky for athletes of all ages
Sports and extreme heat can be a dangerous mix. Heat is the deadliest weather-related hazard in the U.S. And athletes are among those most at risk.
Exercising or playing sports outdoors in extreme heat can add increased stress to your body, putting you at risk of dehydration and heat-related illness.
As our climate warms, the rise in extreme heat is a growing concern among athletes — from Olympians competing in Paris this summer to student athletes heading back to practice across the U.S.
School sports and heat hazards
As millions of student athletes begin outdoor practice this late summer, they’re playing in a warmer world than their parents or coaches experienced decades earlier.
Youth and teen athletes are particularly at risk from heat-related illnesses. Young children sweat less and acclimate to heat more slowly than adults. Children may also ignore or miss symptoms of heat stress or dehydration when playing outdoors.
Learn more: Extreme Heat Risks for Children
According to the U.S. Centers for Disease Control and Prevention, heat-related illnesses are a leading cause of death or disability among high school and college athletes.
With an estimated 7.8 million high school athletes across the U.S., late summer is the time when many head back to football, soccer, field hockey, or track and field practice — and when parents, guardians, and coaches need to be vigilant about the potential risk for exertional heat illnesses.
Human-caused climate change is driving up summer temperatures and making extreme heat events more likely.
More extremely hot days in 212 U.S. cities
To understand the rise in risky heat, Climate Central analyzed the changing frequency of extremely hot days in 242 cities across the U.S. from 1970 to 2023.
The analysis defines an extremely hot day as exceeding the 95th percentile of each location’s average annual maximum summer temperature from 1970 to 2023 (see Methodology).
Across the locations analyzed, this threshold ranged from 66°F in Eureka, California and Juneau, Alaska to 108°F in Palm Springs, California and Yuma, Arizona.
Extreme heat thresholds reflect the hottest temperatures of summer. This analysis tallies the annual number of days that exceed this threshold. As average temperatures rise and heat extremes occur more often, many places experience hotter temperatures beyond the summer season.
The annual number of extremely hot days increased from 1970 to 2023 in 212 (88%) of the 242 locations analyzed.
On average, these 212 locations now experience 15 more extremely hot days than in the early 1970s.
Most of the locations analyzed (172, or 71%) now experience at least one additional week’s worth of extremely hot days than in the early 1970s.
Some 18 cities — mostly in the South and Southeast — now experience at least 30 additional extremely hot days each year than in 1970, lead by:
City | 95th percentile average maximum summer temperature, 1970-2023 (°F) | Change in annual number of extremely hot days, 1970-2023 |
|---|---|---|
Miami, Fla. | 92 | 50 |
McAllen, Texas | 101 | 43 |
San Angelo, Texas | 100 | 43 |
Victoria, Texas | 97 | 42 |
Odessa, Texas | 98 | 37 |
Tri-Cities, Tenn. | 88 | 35 |
Raleigh-Durham, N.C. | 91 | 34 |
Parents, guardians, and coaches: what you can do
Coaches and trainers are entrusted with the health and safety of athletes during practice and competitions. This is especially true for youth or teen athletes who rely more on adults for their overall protection.
Average temperatures and extreme heat events will continue rising without drastic cuts to heat-trapping carbon pollution. Athletes of all ages participating in outdoor sports are at risk from more frequent dangerous heat. Taking effective measures to adapt to a warming world is key to protecting their health and well-being.
These are some of the ways to minimize exposure to dangerous heat:
Promote safe outdoor sport participation. Observe recommendations for the prevention, recognition, and treatment of exertional heat illness, as well as guidelines for preseason heat acclimatization.
Prioritize health. Prior to exercise, athletes should undergo medical screenings for previous heat illness incidents, other relevant conditions, or current illness before determining eligibility to participate.
Be aware of extreme heat conditions. Check temperature and heat risk forecasts, and take note of heat advisories or excessive heat warnings. Use a wet bulb globe temperature monitoring device (which takes into account ambient temperature, relative humidity, wind, and solar radiation) to more accurately measure potential environmental heat stress, and modify activities accordingly.
Stay cool. Avoid outdoor workouts during the hottest part of the day (usually midday). Plan frequent breaks in the shade or a cool area and allow athletes to remove equipment like helmets.
Maintain hydration. Fluids should always be available, not just during designated breaks. Instruction should be given to athletes on eating and drinking appropriately to replace sodium lost through sweat.
Prepare for heat-related emergencies. Educate personnel (coaches, medical staff, and trainers) about preventing and recognizing exertional heat illness and stroke. Develop policies for organized sports and events taking place in hot, humid conditions.
Educate athletes about heat risks. Athletes of all ages should be educated about the signs and symptoms of heat illness. Encourage athletes to pace themselves, monitor their condition, and stop exercise if they feel faint or weak.
LOCAL STORY ANGLES
See the rank of your state’s high school sports safety policies
The University of Connecticut's Korey Stringer Institute (KSI) studies heat stress in sport and is named after the Minnesota Vikings offensive lineman who died from exertional heat stroke in 2001. KSI works with high school athletic associations in all 50 states to promote instituting state-level policies for preventing heat illness that are informed by medical expertise and evidence-based research. The organization ranks states based on their “implementation of evidence-based best practices for preventing and managing the leading causes of sudden death in secondary school athletics.” See where your state ranks in the 2023 evaluation.
Map the influence of climate change on daily heat extremes in your area
Climate Central’s Climate Shift Index system provides tools, data, custom maps, and local alerts that quantify the influence of human-caused climate change on daily temperatures across the globe.
Check local temperature and heat risk forecasts
HeatRisk is 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.
CONTACT EXPERTS
Doug Casa, PhD, ATC
Professor and Chief Executive Officer, Korey Stringer Institute
University of Connecticut
Relevant expertise: exertional heat stroke, heat illnesses, hydration, and preventing sudden death in sport
Contact: douglas.casa@uconn.edu
*Not available July 21-28.
Rebecca Stearns, PhD, ATC
Associate Professor and Chief Operating Officer, Korey Stringer Institute
University of Connecticut
Relevant expertise: exertional heat-related illnesses and heat stroke, sports and heat, hydration
Contact: rebecca.stearns@uconn.edu
FIND EXPERTS
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.
METHODOLOGY
Maximum temperature data (1970-2023) for 247 U.S. weather stations were obtained from the Applied Climate Information System. The extremely hot day temperature threshold for each location was determined based on the 95th percentile of the average annual maximum summer temperature from 1970 to 2023. The threshold temperatures are rounded to the nearest integer in graphic subtitles; precise values used to calculate annual days above the threshold can be found in the graphic footnotes or the data download. The annual count of extremely hot days includes all 12 months. This Climate Central analysis included 247 stations, but five were excluded from the trend analysis due to insufficient data: Dothan, Ala.; Hazard, Ky.; Jefferson City, Mo.; Twin Falls, Idaho; and Wheeling, W.Va.