Isn't it too soon to assume that? Viruses decay faster at higher temperatures so it should have some effect on R0. With other measures like social distancing, masks, and remote work it might lower it below 1.

There are already dozens of severely ill patients on many cities in Brazil, what is the easy to compare metric. The rate of growth of cold and hot cities isn't very different, and hasn't been very different from the untreated growth on the rest of the world.