In this Instructable, I am going to show you how I made a temp and humidity sensor with an Arduino Uno. My end goal is to make one with an Attiny84 and etch a PCB for it. While I do have the parts and pieces to do this, the weather outside is not cooperating. It is hard to etch a board in my garage at less than 10 degrees Fahrenheit. That will be a different instructable for a later date.