In the summer, temperatures average in the 100 degrees Fahrenheit range. It is not unrealistic to expect temperatures as high as 120 degrees at times and up to as high as 130 degrees near the Mexican border. The 100-degree temperatures usually begin around May and do not subside until around the end of October. The heat spawns many dust devils, which are like a mini tornado, but without all the damage. Summer also brings the monsoon rains between July and August. The Sonoran Desert is the wettest of all the deserts with an average of 3 to 16 inches of rain. Rains are often preceded by dust storms consisting of red clay dust and winds from 30 to 50 mph. The rains also bring humidity, making it seem much hotter. Mountain areas average around 70 to 80 degrees in the summer, but mid-range areas may hit 90 degrees in mid-summer.
Although autumn comes around September 22, it is not until October that the temperature usually comes down to a truly comfortable range for most people. The rains all but end at this point and it is often months before rainfall comes again. This means that the humidity all but disappears from Arizona as well making even the warm 90 to 100 degree temperatures feel much more tolerable and people spend more time outdoors. In the steppes and the higher country, temperatures begin to fall and it is not unusual for the higher regions to begin seeing snow, although snowfalls are sporadic.
Winter is the reason most people move to Arizona and its dry climate is a drawing point for many winter visitors. The climate becomes cool at night with averages around 35 to 55 degrees and daytime highs between 60 and 75. While it is rare for the lower regions to go below freezing, there are usually at least one or two nights where it reaches the freezing point and fragile plants must be covered. A dusting of snow has rarely been recorded in lower regions and light amounts in the steppes, but in the high country the snow can accumulate from 1 to 5 feet, making it a destination spot for winter sports enthusiasts.
Arizona is in full bloom during the spring, with winter's rains and melting snow feeding the plants below. The temperatures are mild with weather conditions that are prime for planting as early as March. Early planting is essential as dew point levels often dip to below the 10 degree mark in May and on into June. That means that things become very dry and get too hot for tender crops and flowers to survive. Summer temperatures will arrive in May, a month earlier than in most states.
