Maybe I don't understand. The number of confirmed cases is going up exponentially in all of the warm locations you mention. This is in spite of a lack of testing. How is that evidence of R < 1?
The point is that places like California will experience slow growth which will also decline quickly with the warming weather, not that every place has negative growth right now.
Maybe you should read this from an actual epidemiologist: https://ccdd.hsph.harvard.edu/will-covid-19-go-away-on-its-o...
The article is explaining what the default assumption should be. Empirical data might change that view.