Rarely will you get the appropriate weather in Texas to do an air dry cure. As its been stated above, humidity is the difficulty. If you had 3 days of weather like right now (dry and cool) and suddenly your temp changed to 75* and humid, you'd have to immediately remove your sausage from outside air and finish it by other means.
You can remedy this by building a room specifically for sausage making, which in turn, becomes awesome for other things like salamis, jerky, and cold smoking cheese/fish. You'll need a well insulated room, a dehumidifier, and a source to control temperature. I'll leave that research up to you, as there are 1000's of configurations and opinions.
There is another option: I've found that you can cheat the system a bit and still yield decent results, although its not a 100% "old fashioned" method of air curing. First, you need mother nature to give you a 3 day forecast of mild temps and no humidity. Make your sausage and add your cure as you normally would. Hang your sausage in a room with indirect heat/smoke, bringing temps to 165-180 degrees (which is higher than normal) within the room. To achieve these temps in my smoke house, I had to put a fire box inside the actual smoke room. Keep this temperature for 6-7 hours OR at the 5 hour mark, start squeeze testing to feel the sausage firming on the inside. I like my sausage pretty wet on this inside. After the sausage begins firming up, throw one big log on the fire, shut the door and walk off. Let the fire go out and the sausage slowly begin cooling. As it does, it will cure. After 3 days, remove from smoke house and place on the bottom shelf of your garage fridge, on a sheet pan loosely covered with butcher paper for another 24 hrs. This will help pull some smoke biterness out and also slow the cure process more. Wrap and freeze. Done. It's not bullet proof, but its worked for me several years.
Now one more thing: Your smoke. Smoke should be translucent or light blue, NOT light grey and thick. Light grey smoke (almost like a wet log burning) will yield a sooty awful flavor.