Don’t go by those averages. Regular temps don’t tell the whole story. It’s the heat index that matters in Austin. It’s not out of the question to have 100 straight days over 100 degrees in Austin before the heat index. It’s also not uncommon to be wearing shorts, running the A/C, and eating outside on Christmas. Temps in the 90s can start in early April, and not end until November. It’s a very long time to be hot enough to have to keep towels on your car seats so as not to burn your thighs while wearing shorts. And in the cool season, it’s mountain cedar season, which can be pretty rough for a lot of people. (A lot of people who leave Austin will cite the three big allergy seasons, mold, oak and cedar, as part of the reason for leaving.) When the weather is good in Austin, it’s really good. Everyone’s tolerance of the heat is different, but newcomers often visit during SXSW in March when the weather is pretty great compared to everywhere else, and this gives a false impression of a mild climate.
It might not be as humid as NOLA, but it’s also not as dry as Phoenix. 105 and humid is way harder than 110 and dry when you are outside all day as a student going from class to class.
Austin is at the edge of the Texas Hill Country, for terrain reference. I mentioned Southwest in terms of culture because kids looking at Tulane often place a premium on local cultural experiences. And as the other longtime Austin resident up there said, Austin is not Southwestern. Even (and especially) from a weather standpoint. It’s way (way) too humid to be southwestern.