system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If certain illnesses go dormant in the warmer months, how does it ever exist in a hot area in the first place (Arizona, Florida etc)?
gpt
They don't really go dormant, so much as they're harder to spread around. If a germ needs to be in water to remain infectious, for example, an arid environment will dry it out and leave it exposed, making it harder to spread from person to person.

Separately, some atmospheric conditions help people deal with symptoms, so diseases are less painful or noticable to the infected. For example, a way to help alleviate symptoms of many respiratory diseases like COVID is to breathe in warm, humid air, like in a hot shower. So depending on the environment, people might not know they're sick so people assume there's not much going around. 

We don't know enough about SARS-COV-2 yet to be truly sure about any of those things for it. The variation in symptoms from person to person seems to be immense. We do know that warm, humid weather isn't a cure-all: Brazil is likely going to be a major epicenter very soon given it's poor management of the crisis thus far, and Florida is shortly to be a disaster zone of epic proportions for similar reasons. New Orleans, a notoriously hot and humid city, is also a major epicenter right now.