Arizona, New Mexico, Texas:

The states of Arizona, New Mexico and Texas firmly sit in the US Sun Belt region, home to an explosion of late 20thC population growth courtesy of those searching to live in a warm and sunny climate. Dallas-Fort Worth, Houston and Phoenix are the biggest cities in sprawl and population, but it’s probably majestic nature-made sights like the rock formations of Sedona and just-over-the-border Monument Valley, the Apache National Forest, or the bucket-list Grand Canyon, that you’ll be heading for.

The common factor of the southwest is the dry heat, although parts of east Texas can be humid. In fact, the vast lone-star state has very different weather across the state across the year, often based on on proximity to the Gulf of Mexico. For instance, don’t think that Texan heat lasts all year long, parts of the north have on average 2.5 feet of snow annually.

The southwest offers extreme temperatures, from searing summer heat in the valleys and Chihuahuan and Mojave deserts, to brutal cold inland; winter night time temperatures in northern parts fall well below freezing for three months. But along the coast, things are more temperate, with mid-teen temperatures in the winter, although this far south daytime highs are expected into the low 30s between June and September.

The summer is the busiest time to visit the Grand Canyon, so if you want to avoid the crowds, definitely try for the spring or autumn. Texan autumns are warm, even in November, temperatures reach into the low 20s by day, although it’s a little cooler at the Grand Canyon and Sedona.
If you do opt for spring, be aware that some parts of northern Texas push into Tornado Alley and can be prone to severe thunderstorms and tornadoes. Later in the year, Texas can also be hit by hurricanes swirling in from the Gulf of Mexico.