By Elke Weesjes

Although the weather is finally beginning to cool, memories of soaring temperatures are all too recent for the many homeless caught in heat waves across the nation this summer.

Heat records were smashed from coast to coast in 2015 with temperatures reaching triple digits across the United States. But while most Americans can stay indoors, crank up the air conditioner, or take cold showers, those experiencing homelessness often struggle to stay cool and can fall victim to potentially fatal heat-related illnesses.

Phoenix—one of the hottest cities in the United States—is all too familiar with the impact of extreme weather on its homeless population. This year the city was struck by two massive heat waves—one in June and another in August—with temperatures reaching as high as 117 degrees.

The unsheltered homeless especially struggle during sweltering temperatures. Victor Schaeffer was one of them.

“I keep myself wet constantly when I'm in the sun,” Schaeffer told Al Jazeera America. “I have to, because I've had heat exhaustion every summer for the last six summers. Two times I was really bad, throwing up, I couldn't quench my thirst, it didn't matter how much I drank… I had cramps… It's almost to the point where you're so bad you can't get yourself to the hospital.”

Heat can cause myriad medical problems. Besides heat cramps, heat exhaustion, and heat stroke, it can also exacerbate underlying conditions such as high blood pressure, heart disease, bronchitis, emphysema, and even psychiatric disorders.

Since many homeless people struggle with chronic health issues, mental health problems, and substance dependency, turning up the heat puts them at even more risk.

Phoenix—like many other major cities such as Philadelphia, New York, and Baltimore—has a Code Red policy, the summer equivalent of the Code Blue system used to protect the homeless during frigid weather. Procedures that follow Code Red alerts are designed to help get people indoors, extend shelter hours, and increase the efforts of teams that check on individuals and assess them for signs of medical danger.

Access to cool environments and water is critical during a Code Red. To address these needs and protect those vulnerable to the heat, Central Arizona Shelter Services (CASS) has developed an annual Heat Relief Campaign, which collects funds for bottled water, shelter, and medical care. Shelter teams, together with Phoenix police and other services, work around the clock to distribute water to the homeless during a Code Red, CASS spokeswoman Lindsey Roberts told KTAR radio. “On average, we go through about 1,000 bottles a day,” Roberts said.

The CASS campaign is part of a much larger initiative in the Phoenix metro area and Maricopa County. Called the Heat Relief Regional Network, the partnership was founded by the City of Phoenix and the Maricopa Association of Governments in response to a devastating heat wave that hit Maricopa County in July 2005.

The extreme temperatures killed 45 people—most of them homeless—and the Network was created to prevent similar tragedies. Each summer, it raises awareness about the dangers of extreme heat, coordinates water donation and distribution, recruits facilities to serve as cooling and hydration centers, and provides maps of the Heat Relief Network resources to those in need.

Since its inception, multiple cities in Maricopa County have joined the Network, implementing their own donation and hydration stations. The effort has had good results—the number of heat-associated deaths of homeless individuals has steadily declined in the past five years. It might even serve as an example for other hot states, Rebecca Sunenshine, the medical director for disease control at Maricopa County Public Health Department, told Al Jazeera.

“This is a health issue that we've been battling for a number of years and I do think that this is something that we can help the rest of the country deal with, as global warming does increase the temperatures.”