I'm not so sure why folks on here believe there's evidence to the contrary, citing Florida Texas and California?. I haven't looked at Cali's numbers, but in Florida and Texas-- where the states began opening up over 4 weeks ago-- hospitalizations and deaths are not skyrocketing. They're pretty steady despite some volatility in the data.
California cases keep going up, and deaths have stayed constant.
I think seasonally the flu would be dropping off by now, whereas COVID-19 is continuing to spread without much trouble.
One of the reasons that it was originally thrown out there was that CA/FL/TX didn't get hit as hard as NY/NJ/MI/IL etc. About the only outlier getting hit hard in a warm-weather state was Louisiana. The thought was that weather might have been one of the reasons those states weren't hit hard, and that as things warmed up, those states would drop to near-zero.
Heat may have an impact, but generally this thing isn't going "away" for the summer as people were originally hoping.
More than that, though, what I really wonder, is how effective does the virus transmit in the open air, in the sunlight, in public places? The media assured us that the Spring Break revelry on the beaches in Florida and Texas spelled certain disaster for case counts in those states, but that never really materialized. It's plausible that the virus just doesn't transmit well in the open air with sunlight, heat, and wind. Again, not saying that's a certain thing, but we have at least some evidence that expected flare-ups never occurred.
I have been reading more that transmission is a little harder than thought, i.e. that it generally requires 10-15 minutes in an enclosed space with an infected person to have high likelihood of transmission. The CDC considers these guidelines to call yourself "exposed"
these guidelines to call yourself "exposed" if it's not someone in your household, in your care, or an intimate partner:
Individual who has had close contact (< 6 feet)** for a prolonged period of time ***
***Data are insufficient to precisely define the duration of time that constitutes a prolonged exposure. Recommendations vary on the length of time of exposure but 15 min of close exposure can be used as an operational definition. In healthcare settings, it is reasonable to define a prolonged exposure as any exposure greater than a few minutes because the contact is someone who is ill. Brief interactions are less likely to result in transmission; however, symptoms and the type of interaction (e.g., did the person cough directly into the face of the individual) remain important.
I think if you're walking along the beach and you pass within 6 feet of someone with COVID-19, it wouldn't be considered exposure or high likelihood of transmission.