The temps in Houston are now firmly in the dangerous range during peak summer. When you reach a certain humidity and temperature, your body can't regulate its internal temperature by sweating anymore, you essentially have to have some kind of external input to cool off, that can be cold(er) water, air conditioning, fans (where you can have lower humidity or temperature air blowing over you, or something similar.

If you can make changes to your structure, doing a radiant barrier or some kind of false roof (even a solar shade or something that doesn't block all the sun) over your existing roof to limit the solar heat transfer to your structure can help.

If you can get some insulation for the windows, especially if you can get the foil lined version and direct the foil outside, that will also help.

Local air conditioning (mini splits or single room units) are often less efficient but if you are just focused on making it tolerable, you can do a single room as a cool down room for less money (upfront and in energy cost) vs a whole house or multi room unit. There are 12v units that can be run on a decent size solar setup like used in RV's or campers.