New Mexico use to do emissions on diesels in Bernalillo County, however, it was determined that it was against the law to do so. Refund checks were issued to people who had to pay for being smogged and this requirement was no longer valid on diesels. Now, only gassers are smogged.
I use to live in the DFW area (Flower Mound) and the weather will be warm down there, however you wont deal with the humidity. As far as snow, yea a tad, but more than likely nothing bad. Once in a while you'll have that eastern front hold up down there, but their rare. Your in the desert, so you will see the cool downs at night, nothing bad though.