PHOENIX – If you have ever been to Phoenix, Arizona, you’ve likely seen the saguaro cactus. They’re iconic, often towering 40 feet tall or higher, and are the largest cactus in the United States. According to the National Park Service, the tallest saguaro cactus ever measured was more than 78 feet tall.
Now, these iconic giants are falling. Why? The heat and lack of rain.
Yes, this cactus can withstand pretty hot temperatures and are fairly drought tolerant, but too much of either element can cause these towering cacti to topple over and die.
That’s exactly what’s happening.
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Phoenix has been hotter than normal. In fact, the city has been at or above 100 degrees since June 14.
You’re probably thinking this is typical, but the heat soared to a different level. During the month of July, Phoenix hit 119 degrees on the 19th, 20th and 25th, which are the highest levels ever recorded there. The normal heat for July is 106 degrees on average.
The city is known as “The Valley of the Sun” saw temperatures of 110 degrees or hotter from June 30 through July 30 consecutively. This was a record 31 days of extreme heat, breaking the old record of 18 days.
Even the nights have been hot. On the morning of July 19, a record warm low temperature of 97 degrees was recorded. There have been several nights where the low temperatures fail to dip below 90 degrees.
Even though these cacti can survive the heat of the Sonoran Desert, the nights are crucial for their survival. When temperatures are cooler at night, the saguaro cactus will open tiny pores to take in carbon dioxide and shed retained water. When it’s too warm to do this at night, the cactus then runs the risk of dehydrating.
The saguaro cactus is roughly 90% water. The more water it loses, the more dehydrated the plant gets, resulting in leaning limbs and even the entire plant collapsing. Once the cactus collapses, there’s no coming back.
During the summer, half the rain for the year in the Sonoran Desert comes from the monsoonal rains. The season runs from June 15 through September 30. While reports have shown the monsoon season has begun, it’s been mainly south of Phoenix, leaving the city high and dry. It’s almost two months into the rainy season and many parts of Phoenix are still waiting for the first measurable rain to happen. Only trace amounts have been recorded on very few days.
Stubborn high pressure has been the culprit for the extreme heat and lack of rain in the area. Even with sufficient moisture in place from the monsoon setup, Phoenix still has very little chance for rain over the next few days.
Next week doesn’t look any better. The ridge of high pressure will continue to expand westward into the desert southwest, bringing the warming trend back above 110 degrees with little to no rain.
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