Exactly the reason why Qatar World Cup happened in winter season because the humidity and temperature is not that much of a problem compared if they will commence the games in summer just like what we used to because the heat will become a major problem to the audience especially the players who are playing under the heat of the sun. But even if it's already winter season when the games happened in the recent World Cup, the stadiums still needed a lot of help to cool it down.
Qatar is a country with this hot weather and that's why they had cooling devices even in stadiums otherwise considering the number of fans in stadiums it could be so hard for the visitors to even stay in the stadiums that's why as far as I know most of the games was at night and the world cup was in winter to make sure about the weather but we won't have these problems in America and especially in Canada in 2026.