Desert weather isn't that bad, once you get used to it. The thing is to plan your activities so that the outdoors activities are not done in the peak of the day when it is hottest (in the summer). That means doing them in the early morning or early evening. The rest of the time should be spent indoors as much as possible. Tucson is actually about seven to ten degrees (Farenheit) cooler than Phoenix-it is at a higher elevation. We also have a much lower humidity than most other parts of the country, so that helps.

That said, we can get pretty cold at night in the winter. Low humidity also means few clouds. That means that the solar energy (ie. heat) that builds up during the day escapes into the upper atmosphere at night without clouds to trap it. Like I've said, a number of migrants do die in the winter attempting to cross the border in the more remote areas.