I live in a desert where the temperatures range from 90 to 113 degrees in the later morning/early afternoon.  The humidity on average is in the low 20%. In order to protect my juniper I put it out in the morning at 6 am when its 80 degrees and by 8 am its already in the 90s. I leave the plant out until it reaches 100 degrees at 12 pm and then transfer it to the back porch shade where the sun will only hit it at 4 pm (108 degrees). I'm afraid that I have been overwatering it since I mist it every hour in an attempt to compensate for the lack of humidity in my area, but now I can't tell if the browning of my juniper's foliage is from overexposure of the sun, lack of humidity, or that I'm overwatering it. Please help and possibly suggest what a good routine would be for my bonsai. 

Not too much sun that's for sure, possibly not enough water. I would be watering twice a day at least if it was that hot. Does not look much wrong with it, after all it is a living plant and needles do die. Misting is not watering, and I would not be doing it, when I water I go over the foliage at the same time,

Desert may be an issue. Are there any junipers growing naturally in the area or in gardens around you? Do you get a real winter there?