Taylor Swift is postponing her second show in Brazil this weekend after a fan died the day prior and amid scorching temperatures there in the city that she deems too dangerous.

The pop star announced the decision Saturday, not long before she was scheduled to take the stage there at Rio de Janeiro's Estádio Olímpico Nilton Santos -- where she had just performed Friday ... and where a young fan lost her life ahead of curtain call.

Taylor says she's hitting pause for her performance tonight -- which would've marked night #2 of a 3-show stop there in Brazil -- and says her fans' safety comes first before anything.

She says, "I'm writing this from my dressing room in the stadium. The decision has been made to postpone tonight's show due to the extreme temperatures in Rio. The safety and well-being of my fans, fellow performers, and crew has to and always will come first."

No word on whether she's going to proceed with Sunday's show -- for now, it looks like Rio's expecting a high of 84 degrees ... whereas it's in the 90s today, and hit 88 with high humidity yesterday.

Of course, she's being praised for this move ... as many were wondering how she could possibly go forward after the tragedy from Friday night, which Taylor obviously addressed as well. She said she was heartbroken over it, but also said she wouldn't talk about it onstage.

The fact that she was apparently just going to proceed with her regular show and not address the fan's death in person -- despite already having done so online -- didn't sit well with some -- and it seems Taylor/her team realized that ... wisely opting to stop down.

It appears that even before Taylor became aware of the fan's death -- which has been speculated to be over a heatstroke of some sort -- she already suspected something was wrong. There's footage of her at Friday's show demanding that the fans be handed water.