As glob­al tem­per­a­tures rise, ex­treme heat could threat­en ath­letes, fans, work­ers and of­fi­cials dur­ing this year’s World Cup games.

Six­teen cities across the Unit­ed States, Mex­i­co and Cana­da will be host­ing the 2026 World Cup in June and Ju­ly. On av­er­age, Ju­ly is the hottest month of the year for the con­tigu­ous U.S., ac­cord­ing to the Na­tion­al Ocean­ic and At­mos­pher­ic Ad­min­is­tra­tion, and it’s on­ly got­ten warmer since record-keep­ing be­gan in 1895. Wet bulb globe tem­per­a­tures, which fac­tor hu­mid­i­ty, wind speed, sun an­gle and more, could ex­ceed 90-Fahren­heit (32-Cel­sius) in the af­ter­noons in the Texas cities of Dal­las and Hous­ton and Mon­ter­rey, Mex­i­co, re­search shows.

“Al­most all of the host lo­ca­tions, 14 out of 16 of them, ex­pe­ri­ence lev­els of ex­treme heat, which could be po­ten­tial­ly dan­ger­ous to play­ers, match of­fi­cials and pos­si­bly spec­ta­tors,” said Don­al Mul­lan, a se­nior lec­tur­er at Queen’s Uni­ver­si­ty Belfast who led a pa­per last year ex­am­in­ing the heat risks of this year’s host cities. Some sta­di­ums have the ad­van­tage of be­ing ful­ly cov­ered, re­duc­ing the risks.