Madera Canyon Road climbs from the Sonoran Desert floor in Green Valley at around 2,700 feet where the temperature in summer may be from 85° to 105°F (30° to 40°C) to 5,500 feet where the temperature will be some 20°F cooler. Monsoon rain storms begin in early July and continue through August into September. The storms do not occur every day and usually the cells are small and highly localized, but when they are over you, prepare for hail and a brief downpour with falling temperatures. Dry washes fill with rushing water and Madera Creek can flood so be careful. In winter, expect snow above 5,000 feet and temperatures near freezing in the canyon. For all these climate conditions, be prepared with adequate foot gear and layered clothing.
MADERA CANYON CLIMATE
The Five Seasons of Madera Canyon
People often imagine Arizona with a constant hot, dry climate. Arizona’s geographic location, just north of 35° latitude, is common to many of the world’s arid regions. In fact, Arizona has distinct seasons. The Sky Islands actually have five seasons: spring, dry-summer, wet-summer, fall, and winter.
Temperatures and precipitation vary widely with the season and altitude. Every 1000 feet of elevation gain produces a drop in temperature and increased moisture equal to traveling 150 miles north. A trip from the valley floor to the top of Mt. Wrightson is like driving from southern Arizona to Montana!
The Five Seasons:
Spring - Spring normally brings gentle rains with northwest winds and rising temperatures in late February through April. Daytime temperatures: 70 - 80°F in the Santa Cruz Valley to 50 - 60°F in the canyon.
Dry-summer - Usually starting in May, dry-summer brings extremely low humidity, little to no rainfall and high temperatures through June. Daytime temperatures: 100 - 110°F in the valley to 80 - 90°F in the canyon.
Wet-summer - A shift in prevailing northwest winds to the south in July announces wet- summer, locally called the “monsoon.” Tropical moisture is drawn into the region and humidity rises sharply. The moisture combines with intense daytime heating and mountainous terrain to produce strong thunderstorms. Daytime temperatures: 100 - 110°F in the valley to 80 - 90°F in the canyon. Rainfall can be locally heavy!
Fall - Fall begins as winds shift back to the northwest in mid-September. Moisture flow from the south stops. Humidity drops and temperatures soar before dissipating by mid-October. Daytime temperatures: 70 - 80°F in the valley to 50 - 60°F in the canyon. Little rain is expected before mid-November, but El Niño events and tropical cyclones can bring fall rain into southern Arizona.
Winter - In mid-November winter usually arrives with cool temperatures and regional precipitation. Northern storms sweep down across Arizona; some bring rain. The coldest fronts can produce considerable snowfall on the peaks. Daytime temperatures: 60 - 70°F in the valley, 40 - 50°F in the canyon. Temperature may drop below freezing in the canyon during storms!
Geography affects Arizona’s weather -
Arizona lies between active/wet weather patterns to the north in winter and to the south in summer. Seasonal rainfall is influenced by two sub-tropical high pressure systems:
North Pacific High
When strongly in place, the North Pacific High over the Pacific Ocean extends dry conditions over the region. In winter, this system can force the storm-track to the north, reducing winter rainfall in southern Arizona. A weakening of the Pacific High allows storms to track further south and brings vital precipitation down from the Gulf of Alaska to the desert and Sky Islands.
In summer, precipitation is tied to the strength and position of the Bermuda High over the Atlantic Ocean. A strong high can expand across the Gulf of Mexico into the Southwest, bringing a strong flow of moisture up from the sub-tropical south and creates wet-summer thunderstorms.
Mountains create their own weather -
Weather fronts moving through southern Arizona lift to pass over mountain ranges. This uplift cools the air, condensing moisture into clouds which often produce rain or snow, even when the desert below remains dry.