The average high temperature in Austin is below average human body temperature, and only a little above average human skin temperature during the hottest part of summer. I'd thus expect that the virus would have no trouble with Austin heat when it is in/on people or airborne.

Also, don't most homes and businesses there have air conditioning?

Oh wow, that's disappointing. I was hoping once summer got here, it'd go away and people would forget about it. Sorta like Swine Flu, Zika and Ebola was supposed to kill us all but now we never hear about it.

Most Singapore buildings and its public transport system are fully A/C.

If scientists actually thought summer heat would kill the virus, that’d change.