Tourists shelter from the sun in front of the Sforzesco Castle in Milan, Italy, on Tuesday. Weather alerts, forest fires, melting pavement in cities: A sizzling heat wave has sent temperatures in parts of central and southern Europe soaring toward 104 degrees Fahrenheit (40 degrees Celsius) in some places. Luca Bruno/AP hide caption
Marvin Cox, community outreach director with the Metropolitan Action Commission on June 25, in Nashville. As temperatures reached into the upper 90s, the Metro Action Commission was offering free window AC units to seniors, families with young children and people with medical conditions. Mark Humphrey/AP hide caption
A man affected by the scorching heat is helped by another Muslim pilgrim and a police officer during the Hajj pilgrimage in Mina on June 16. Fadel Senna/AFP via Getty Images hide caption
A rainbow appears behind a flooded neighborhood in Jamaica Beach, Texas, on Thursday. Brandon Bell/Getty Images North America hide caption
People rested at the Oregon Convention Center cooling station in Portland, Oregon during a record-breaking heat wave in 2021. FEMA has never responded to an extreme heat emergency, but some hope that will change. (Photo by Kathryn Elsesser / AFP via Getty Images) Kathryn Elsesser/AFP via Getty Images hide caption
People in the streets of Rom in June 2022. Heat-related deaths in Europe have increased by about 30% in the last 20 years, according to a new report. Alessandra Tarantino/AP hide caption
NASA reports July 2023 as the hottest month on record. David McNew/Getty Images/David McNew hide caption
The National Weather Service issued warnings and advisories for a heat wave blanketing the Pacific Northwest this week. Screenshot by NPR/National Weather Service hide caption
EMTs help a patient in Austin, Texas, this week. The man had passed out near the state capitol and was dehydrated. Cities with few trees and areas of shade are hotter during heat waves. Brandon Bell/Getty Images hide caption
Yogurt-based drinks such as the lassi from India are go-to beverages for cooling down in the hot summer. The glasses at left add mango to the recipe. Chona Kasinger for NPR hide caption
A man overlooks downtown Phoenix at sunset atop South Mountain on Sunday. Some slight relief may be on the way as seasonal thunderstorms could drop temperatures in Phoenix on Tuesday. Matt York/AP hide caption
A sign warning of extreme heat danger in Death Valley National Park on July 15, 2023 David McNew/Getty Images hide caption
In 2006, Waikiki Beach was near empty of swimmers due to a sewage spill which diverted millions of gallons of raw sewage into a nearby canal. Marco Garcia/Getty Images hide caption
Austin, Texas, construction workers dig on a hot day in August 2021. Last month, Gov. Greg Abbott signed a bill that overturns local ordinances in some Texas cities that mandate regular rest breaks for such workers. Blaine Young/Public Health Watch hide caption
An air conditioner undergoes repair earlier this month in Austin, Texas. Record-breaking temperatures continue across large swaths of the U.S. Brandon Bell/Getty Images hide caption
The sun rises above the Atlantic Ocean as waves crash near beachgoers walking along a jetty. Ocean temperatures averaged five degrees warmer around South Florida beginning in July. Wilfredo Lee/AP hide caption
Traffic warden Rai Rogers mans his street corner during temperatures as high as 106 in Las Vegas, Nevada on Wednesday. Frederic J. Brown/AFP via Getty Images hide caption
As the heat breaks records, remember that preventing heatstroke or heat exhaustion takes planning ahead to ensure you stay hydrated and can cool off frequently. David J. Phillip/AP hide caption
Phoenix is on track to surpass the city's heat wave record of 18 consecutive days of 110 degrees and above. Caitlin O'Hara/Getty Images hide caption
Nurse Katie Leonard uses a kayak to bring supplies to Patsy Costello, 88, as she sits trapped in her vehicle Dec. 31 on Astrid Drive in Pleasant Hill, Calif.. Costello drove her car on the flooded street thinking she could make it, but it stalled in the two feet of water. Jose Carlos Fajardo/Bay Area News Group via AP hide caption
Heat wave chuchart duangdaw/Getty Images hide caption
There's nothing stinky about the salty sweat dripping from your face after a run. It's just your body throwing off otherwise dangerous heat. Werayuth Tessrimuang/EyeEm/Getty Images hide caption
Members of the Ornelas family put on plastic raincoats as wind and rain pummel the area on Friday in Julian, Calif. A tropical storm near Southern California brought fierce mountain winds, high humidity, rain and the threat of flooding to a region already dealing with wildfires and an extraordinary heat wave. Gregory Bull/AP hide caption