your wifes body is reacting to the difference in body temp,she needs to drink plenty whilst working in this heat,have your wife discussed with her boss the laws on working in such temps,there should be by law a where it states the temp a person should work in before it becomes dangerous,in my old job we all walked out for two days .
If she'sanything like me, Its the layer of sweat that heat causes that's making her cold. The body sweats too cool itself off, and when you're in 105 temps odds are it's sweating a whole lot! The layer of moisture will be ultra sensitive to any kind of breeze or tempurature drop. Tell her to try drinking ice cold water as often as she can to cool herself off internally before her body gives the signal to sweat away the heat.