Are you planning to move to a desert community for retirement? If so, you know that regular snowfall is not really going to be an issue anymore, if you're moving from the north, nor will year-round humidity be an issue. But that doesn't mean the climate will be perfect for your car. In addition to summer heat during the dry part of the summer, you'll still have a few phenomena to deal with that require you to rust-proof your car.
Monsoon and Tropical Humidity
The southwestern deserts of the United States are subject to the North American Monsoon, a mid- to late-summer mini-season that sees sudden downpours and intense humidity. Some parts of the region have it worse than others, and the humidity, rainfall, and splashing from street flooding can all expose your car to some of the worst rust-forming conditions possible.
In addition to that, much of the Southwest is subject to storms from remnants of Pacific hurricanes and tropical storms that cross northeast over Baja California. These too bring humidity to rival what you'd find in the South, Midwest, or northeastern United States.
Those Trips to the Beach
Eventually the heat is going to get to you during the summer, and you'll head off to the beach either in California, the Gulf of California in Mexico, or southeastern Texas. Salty air and morning fog in these areas can create the right conditions for rust to start forming on your car. You have to protect your car from these conditions with rust-inhibitor spray. While you might not be at the beach for long, it can be enough to sow the seeds of corrosion.
Mountain Snow and Salt
Just because you're in the desert doesn't mean you'll no longer see snow. Some areas of the desert floor can get an occasional dusting; this isn't much of an issue. But if you drive up into the mountains, you can encounter pine forests and woodlands covered with snow. Road salt and moisture from melting snow again can cause rust to form on your car. Plus, if you go traipsing around in the snow and bring a pet with you, you're going to have snowmelt inside your car, too.
Whether you're bringing in your current car or purchasing a new one in the desert, bring it into a repair shop and have the mechanics spray a rust inhibitor on the car. Your car will last longer and look better over the years.