I heard that about 1000 people fainted in that concert because they didn't allow people to bring water bottles so they would buy overpriced water bottles in the venue (which is against the Consumer Defence Code in Brazil).

edit: and people did not buy the water bottles because nobody wants to pay, like, more than R$10,00 in a water bottle that costs a few cents if you just bring tap water from home (incredibly, in most of the state of São Paulo, where the show happened, tap water is completely safe as long as it is coming directly from the grid, and not from your home reservoir)

edit: also, in Santos (a coastal city near São Paulo), some street thermometers measured 50°C on saturday, as shown in the local news channel "A Tribuna" (The Tribune). The increase in temperature is probably due to the boiling hot asphalt of the streets.