The warm, moisture-filled air runs into the Mogollon Rim and other mountains in central Arizona and rises further to form thunderstorms, bringing desperately needed rains to northern Mexico and the Southwest United States. As the moist air flows into Arizona, it heats up and rises. To replace that rising air, cooler moisture-laden air rushes in to fill its place,, predominately from the Gulf of California (Sea of Cortes), and secondarily from the Gulf of Mexico.

As the summer sun heats up the deserts of northern Mexico, hot air at the surface rises. Rains in the summer are dominated by the North American Monsoon which runs, officially, from June 15–September 30. In general, there are two main times of the year when Arizona looks for precipitation, the summer and winter. The nature of rain in Arizona: aka how’d it get so drought-y? Basically, this is a long-winded way of saying the current drought in Arizona and the Southwest is bad no matter if you look back 10 years, 100 years, or 1,000 years. Other especially bad droughts occurred in the late 1500s and late 1200s (known as the Great Drought). Going back even farther than THAT by using tree rings across the Southwest as stand-ins for soil moisture, the current drought over the entire region is one of a handful of the worst droughts in the last 1200 years. Looking back even farther by using a drought indicator known as the Standardized Precipitation Index, the current drought in Arizona is also the worst on record back to the late 1800s. Current conditions are among the driest on record, which stretches back to the late 1800s. The Standardized Precipitation Index for Arizona from 1895-2021 highlighting wet and dry periods over time. However, 99 percent of the state still remains in some level of drought still. Thankfully, heavy rains, especially during the second half of July, has resulted in drought improvements by the end of the month with only around 50 percent of the state in D3 or D4 drought, and only 8.6 percent in D4. And frankly, no previous time in the 21 st century even comes close to matching that drought situation in the state. All of these numbers are the highest since 2000, the start of the current tracking system, the U.S. In fact, almost 58% of the state was in D4 drought during the middle of July. Arizona drought statsĪt the start of July, 99 percent of the state was in drought, with a shocking nearly 90 percent of the state in the two worst categories of drought-D3 and D4, extreme and exceptional drought. US Drought Monitor image from Data Snapshots on . Many areas were in 'extreme' (bright red) or 'exceptional' (dark red) drought. Most the West was at least 'abnormally dry' (yellow). The US Drought Monitor map from August 3, 2021, showing the locations and severity of drought.

Rain totals phoenix