It's not going to be hot at all; September is springtime in Brazil. Temperatures in the mid-70s in the daytime, 60s at night, and dewpoints in the 50s. It's a night game, too.
On September 6th last year, gametime temperature was 63, wth a dewpoint of 57. Year before, gametime temp of 59, dewpoint 55. 2021, 63 and 60. And so on...
The climate will be cooler that time of year in Sao Paolo than in Green Bay. In Green Bay, September 6 was considerably warmer and more muggy than Sao Paolo each of the last several years.