It's very warm and even warmer in the northern part of the country. It's not like CV19 is only occurring in the south. It's spreading rapidly in Sao Paulo and Rio because they are the largest cities but its also prevalent in the north, even in the Amazon basin. What's happening there absolutely does not fit into the "warm weather halts the spread of the virus" narrative.
https://www.nytimes.com/interactive/2020/world/americas/brazil-coronavirus-cases.html