Sonoran Desert Climate
The sunlight of the Sonoran desert changes during the day and it gets hotter. Seasonal temperatures range from an average of 52º F in the winter, to 86º F in the summer. In some seasons the temperatures can reach 32º F at night. In some portions of the desert, near the tip of Mexico, the temperature can reach a high of 134º F in the shade.
The Sonoran desert is one of the wettest deserts in North America and averages from 3 to 16 inches of rain a year. It has two rainy seasons, one in the summer and another in the winter. The summer rains are short and heavy and are often followed by a rainbow. The winter rains are longer and lighter and are more widespread.
There are a lot of sand dunes and grasses in the desert. There are also a lot of cacti, herbs, thorny and thornless shrubs. The creosote bush is the most common plant, and the saguaro cactus is the largest and the most conspicuous plant in the desert.
Many desert animals, such as bighorn sheep, pocket mouse, and pronghorn antelope (an endangered species) use cacti and other vegetation as a shelter from harsh weather and as a source of water. The bighorn sheep has adapted to the desert, because it has big feet, good for the rough terrain, and only needs to drink every few days. The pocket mouse has adapted to the desert, because it is very small, is sand colored, and can run fast from predators. It also doesn't need to drink because it gets all the water it needs from the food it eats and retains its urine.
The latitude of the Sonoran Desert ranges from 25º to 33º North, and the longitude ranges from 105º to 110º West.
The Köppen classification of this climate is BWh, where B stands for a dry climate, BW stands for an arid climate with annual precipitation usually less than 15 inches (40 cm.), and h stands for a dry and hot climate with a average annual temperature over 65° F.
Even though the Sonoran desert is one of the hottest North American deserts, it has lots of diverse vegetation and wildlife due to its two rainy seasons.
by Daniel F. 2003
"American Semidesert and Desert Province", http://www.fs.fed.us/colormap/ecoreg1_provinces.conf?108,295 (1/7/03).
Physical Aspects: Climate of the Sonoran Desert."
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Ecoregions - - Sonoran Desert (NA 1310)."
The Sonoran Desert has many different climates and plants. This desert gets 120 to 300 mm of precipitation each year, mostly as rain. Daytime temperatures can reach or go over 40° C during the summer months of May through September. The rain falls during two wet seasons. One rainy season occurs from December through March and the other from July through September.
Winter rainfall is higher in the western part of the desert, and lowest in the southeast. The Upland Sonoran Desert has regular amounts of winter and summer rainfall. Although winter frosts are common there, they are not extreme. Where the Sonoran desert merges with the Mojave desert in the northwest, summer rainfall is usually scarce. The Arizona Upland has five seasons. There is the summer monsoon from early July to mid-September. Autumn exists from October to November with warm temperatures and low humidity. Winter is from December to February and has mostly sunny, mild days, with some storms with wind, rain and cool temperatures. Spring is from late February to late April. The temperatures are mild with little rain. The fore-summer drought occurs in May and June. The temperature is high and the humidity low. There is no rain in most years.
The Lower Colorado Valley region of the Sonoran desert is the hottest and driest. Annual rainfall is 50 mm or less. Summer temperatures are usually around 50° C. Sand dunes and drought tolerant shrubs with some succulents are found in this region. One of the driest areas in North America lies in the western Sonoran near the Desierto de Altar. The region gets less than 9 cm of rain per year and droughts can last for more than 2 years.
In Sonora, Mexico the desert has a wetter summer rainy season with a drier winter. Drought deciduous plants are common in this area.
The Sonoran desert on Baja has cool moist weather in the winter. Summer isn't quite as hot as most of the Sonoran desert because of the cooling effect of the Pacific Ocean. Moisture from fog and dew allow epiphytes to grow on the desert plants. Many different types of agaves and yuccas grow in this region.
The Köppen classification for the Sonoran Desert is BWh. The B stands for a dry climate where rain evaporates before it falls on the desert floor. There is no water surplus in this type of desert, therefore no permanent streams originate from this zone. W stands for an arid climate. BW, therefore, is an arid climate with an annual precipitation usually less than 40 cm (15 in.). The h designates that the average annual temperature is over 18° C (64.4° F)
Dimmitt, Mark. "Flowering Season in the Sonoran Desert", http://desertmuseum.org/desert/exh_flowering.html
"Sonoran Desert Naturalist Homepage", http://arizonensis.org/sonoran/index.html
"Sonoran Desert", http://www.azstarnet.com/~desertd/sonorn.html