articleThe Brief Extremely hot weather and thinner air create challenges for lanes to safely leave the runway. Scorching temperatures in some U.S. cities resulted in a few major airlines cancelling flights and reimbursing travelers who gave up their seats. On extremely hot days, thinner air can make it tougher for aircraft to get off the ground safely. Sweltering temperatures are commonplace in certain desert-like areas, and the type of hot days that might affect flights are becoming more frequent in Phoenix and Las Vegas. In 2017, American canceled dozens of regional flights in Arizona as temperatures in Phoenix climbed to 120 F.A year later, in July 2018, several airlines moved passengers at Denver International Airport to later flights as temperatures reached 98 F, the AP reported, citing KDVR-TV in Denver.