As someone from the swamps of Louisiana, who has spent considerable time in South and Central Texas, I can say that I was speaking with full understanding of what hot really means. I'll be outside in the middle of July, in the shade for noon to 3.

Concrete and asphalt offers no joy and life with which I might forgive the sun though. I would suggest the morning or late night hours for the crushing city. Regardless, as the other poster said, inside offers a plethora of activities and space for creation. Learn, sculpt, knit, whatever.

Build more you. On the off-chance that you can take something with you when you die, it's about the only option.