In the shadow of Mount Lemmon just north of Tucson you'll find an oasis from the desert heat below. At nearly 6,000 feet higher than Tucson, the area around the summits of the Catalina Mountains have a very different climate than the surrounding terrain. The climb up to the town of Summerhaven near the summit, for instance, involves passing through several different climate zones, a transition equivalent to driving from Tucson to Banff, Alberta, in terms of elevation.
An extensive network of trails wind through the area, and one of the trails that rangers recommend is the Sunset Trail, part of the Sky Islands Traverse. Leaving from a well-marked trailhead a few miles past the ranger station, the trail can be done as an out-and-back, one of several loops, or a one-way trip with a car shuttle if you park a vehicle at Marshall Gulch picnic area. From the spacious trailhead parking lot, the trail first follows a dirt road used by summer home residents and then branches off to a singletrack that winds around and down to a small creek and picnic area.
Running water is a rare here, so after a mile or so of hiking, the sound of the cascades of Marshall Gulch is welcome indeed. A nice view of one of the cascades can be seen across the gulch. Along the way, several vistas looking down the valley toward the desert below make this a rewarding little hike for very little investment!
Note that this area can receive significant snowfall in winter, though it tends to melt quickly. Dress appropriately for the season and weather conditions, as it is significantly cooler here than in Tucson at all times of the year.