As the nation heads into fall and winter, many of us are happy to leave the brutal heat of the past summer—the worst yet on record—behind. But for patients living with sickle cell disease, the onset of cooler weather is a specific relief. Extreme heat isn’t just uncomfortable for people with sickle cell; it can have a brutal effect on their health.
Sickle cell is an inherited condition that distorts normally round, flexible red blood cells into a stiff, sticky crescent shape resembling the farm tool that gives the disease its name, the sickle. The hallmark of the illness is the pain crisis, which strikes without warning when sickled red blood cells block blood flow and can last hours or days. An estimated 100,000 people in the U.S.—including 40,000 children and adolescents—struggle with the disease each year, with Black Americans making up more than 90% of those with the illness. The Centers for Disease Control and Prevention says the illness can shorten a lifespan by nearly 20 years.
Tell Congress: Protect Youth Athletes From Extreme Heat and Dirty Air
Climate crisis, extreme heat, and sickle cell
The summer of 2026 hit record highs in the U.S., according to new data from the National Oceanic and Atmospheric Administration—the warmest in 132 years. Temperatures over the summer rose to three degrees Fahrenheit above average, beating the previous record set in 1936 and tied in 2021 by 0.4 degrees.
“We now live in a completely different climate than the one that existed 50 years ago. Heat records were shattered in all parts of the globe this summer, from the United States to Europe to Asia,” says Dr. Marc Alessi, a climate scientist at the Union of Concerned Scientists.
“When you’re in hot weather, you are losing water faster. Your body fluids are being reduced. That has an impact on the red blood cell; it tends to make them stick together and block vessels. It’s bad with anybody, but it really makes it a significant problem for the person with sickle cell disease… This reduced flow of the blood because of this clumping causes pain, so it possibly puts the person in a pain crisis,” explains Milford Greene, PhD, retired Director of Health Affairs and Clinical Services at the Sickle Cell Foundation of Georgia.
Pediatric sickle cell and heat
Most people in the U.S. with sickle cell disease learn they have it at birth: All 50 states and the District of Columbia have required newborn screening for the disease since 2006, using a few drops of blood from a heel prick. Symptoms usually start around five or six months of age and vary widely from person to person.
For children with the disease, their lives can be shaped by a lack of predictability in symptoms. They may miss school more often than their peers, and their pain can mean missing out on important activities, time with friends, or milestones such as a high school graduation.
Milford adds that children with sickle cell may also be at higher risk for pain crises exacerbated by extreme heat, especially school-age children. “In certain states, it is going to be immensely concerning for kids to go to school in places where they don’t have a constant temperature, or they can’t dial down the temperature relative to the exterior temperature,” Milford says. “So, what do you tell parents? First of all, you want to educate them to make sure that they understand that their children are at some risk in places like from Arizona over.”
An estimated 41% of U.S. public school districts need to update or replace heating, ventilation, and air conditioning (HVAC) systems in at least half of their schools, leaving tens of thousands of buildings without adequate cooling.
What families can do
Dr. Frank Gonzalez, pediatric emergency medicine physician at Children’s Hospital Los Angeles, says there’s strong research to suggest that pain episodes increase with heat due to dehydration. He is a co-author of “Weather-Related Exposures and Emergency Department Visits for Pediatric Sickle Cell Complications,” a report published in Pediatric Emergency Care in May.
He suggests parents and caregivers take precautionary measures. “Making sure that your kid is hydrated, that they have access to water, that if they’re going to school that they are allowed the opportunity and are encouraged to be drinking water throughout the day so that they don’t become dehydrated,” he says. Access to air conditioning is helpful, but interestingly, he cautions against rooms that are too cold, as that can also trigger pain.
Another precaution to take is to exercise indoors during hot weather. If the school gym is cool enough, this means students can limit exposure to heat while maintaining an active lifestyle.
Dr. Gonzalez wishes sickle cell disease were more talked about, and especially the impacts of various environmental exposures like fires and air pollution, not just heat. He adds, “The complications are so devastating, and we see these children in particular in so much pain.”
Tell Congress: Protect Youth Athletes From Extreme Heat and Dirty Air