Yep - Lackland AFB is right on the outskirts of San Antonio...that's where Basic Training is. Special Training (Security, Computers, Aircraft Mechanic, etc) is done at other bases.
I did my basic training middle of August through end of September...close to the worst time of year to be marching and standing outside in that part of the country...luckily PT was early mornings (up at 4am, on the grounds for calisthenics and running by 4:30)