Allergies are bad in Austin because, unlike a lot of Texas, Austin is very green & hilly. There are lakes and rivers, and therefore there are trees and other foliage. Since it rarely freezes in Austin, nothing really dies out and counts can get quite high for specific pollens. And unlike San Diego, there’s not a coastal breeze to blow things away. Surprisingly, Austin is not that humid – there are a few weeks when it’s sticky, but mostly it’s a dry heat (and it does get HOT!).