Arizona’s dry desert landscape is particularly vulnerable to flash floods. A rainstorm miles away can lead to a flash flood in an area full of completely unsuspecting people. Pacific hurricanes that hit Mexico can cause higher than usual rainfall in the typically dry summers. If you’re caught in a flash flood in Arizona, experts say it’s best to seek higher ground rather than try to outrun the flood. Keep reading to find out more about the more intense flash floods in the state.
1. Arizona’s Deadliest Flash Flood: The 1970 Labor Day Flood

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Labor Day is a US holiday when people take the weekend off to go camping, spend time with family, and enjoy life. But in 1970, that day was a sad one for many in Arizona. Over 1 day, more than 11 inches of rain fell on the Mogollon Rim, a stretch of mountains to the northeast of Phoenix.
Despite the Arizona Weather Service office putting out several warnings, people camping near the mountain range didn’t get a warning about flash floods in time to escape. 23 people died, many in their cars, trying to outrun the flood or get to higher ground. Experts cited the transitive nature of camping and the remote location of the campers as a reason why they didn’t get a warning in time. As a result of this event, the Weather Service decided shored up their efforts to educate campers about flash flood risks by placing pamphlets and informational signs at campground offices and tourist visitor’s centers. Nowadays, many campground offices at state, national, and county parks display weather forecasts with warnings about things like wildfire danger, flash flood danger, and other dangerous conditions.
2. The Worst Tropical Cyclone in Arizona’s History: Tropical Storm Octave

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Arizona is subject to the aftereffects of tropical storms and hurricanes that originate in the Pacific Ocean. The brunt of these storms hit Mexico, but their remnants can cause a ton of rain in the normally dry state. In a period of five days between September 28 and October 3, 1983, Tropical Storm Octave dumped more than six inches of rain in “The Valley of the Sun,” AKA, the Phoenix Metropolitan Area. This caused the Gila River to overflow, flooding the important I-10 highway. The flooding was so bad that residents of two small towns, Stanfield and Maricopa, had to be rescued from their roofs by the National Guard. Unfortunately, 14 people died in the floods.
In Tucson, 8 inches of rain fell, creating a flood of nearly 8 feet in some areas. In small towns near the Mexican border, dams burst, and residents had to save their towns with shovels, sandbags, and their own hard work. The storm put other small towns completely underwater. One-seventh of the state’s total cotton crop was destroyed by the storm. 10,000 people were left without homes temporarily. Nearly 1,000 people were injured and 3,000 buildings were destroyed. The damage from the storm cost $500,000 then, which would be nearly $1.5 billion in today’s dollars adjusted for inflation.
3. The January 1993 Floods

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In January 1993, the Phoenix area received rain from several Pacific storms. Throughout the month, different areas of the Phoenix Metro Area flooded. Perhaps the worst was on January 19th when the typically dry Salt River developed into a roaring flood, flooding a landfill and bringing trash downstream with it as it flowed. In other areas, washes flooded, trapping residents of smaller towns in their cars, and stranding them in their houses. 8 people died from these floods that affected the state over a period of 10 days that month.
4. Sept 8, 2014 Floods

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On September 8th, more than five inches of rain fell in Arizona over 8 hours. 200 homes in Mesa, Arizona were inundated with water. One pregnant woman floated on a raft to the hospital when she began to have contractions because the roads were impassable. On the essential highway for the region, I-10, freeway pumps failed to work, effectively turning the highway into a lake. Drivers were forced to abandon their cars for higher ground and watch as they floated away. Other highways were also forced to close due to the flooding. Two drivers, one in Tucson, and one in Pinal County died in the flooding.
5. Hurricane Rosa

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In early October 2018, Hurricane Rosa, another Pacific Hurricane that hit Mexico, dumped its remnants on Arizona. This resulted in the city of Phoenix’s eighth most rainy day ever. Many who attempted an early morning commute found lakes where roads used to be. Some people had to be rescued from their cars, and hikers were warned not to use slot canyons in the area and to be aware of the flash flood risk. Luckily, no one died in this event.
Are There More Flash Floods in Arizona Now?

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Climate scientists say that it is normal for Arizona to experience heavy rainfall from time to time, even though it is a desert. However, they say there is definitely a trend of increasingly wet weather in the area, in addition to more extreme storms. They believe that climate change may be contributing to creating larger, stronger, and more damp storms that last longer and cause more rain. They say that warming oceans are allowing these Pacific Hurricanes to come further north, affecting areas like Southern California and Arizona more often.
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FAQs (Frequently Asked Questions)
What was Arizona's deadliest flash flood?
Arizona’s deadliest flash flood was The 1970 Labor Day Flood.
How many people died in the 1970 Labor Day Flood in Arizona?
23 people died in the 1970 Labor Day Flood in Arizona.
What was the worst tropical cyclone in Arizona's history?
Tropical storm Octave was the worst tropical cyclone in Arizona’s hsitory.
How much did the damage from tropical storm Octave cost?
The damage from tropical storm Octave cost $500 million in Arizona in 1983, which would be $1.5 billion in today’s dollars.
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Sources
- Wikipedia, Available here: https://en.wikipedia.org/wiki/Tropical_Storm_Octave_(1983)
- National Weather Service, Available here: https://www.weather.gov/media/publications/assessments/Arizona%20Floods%20Setember%201970.pdf
- (1970)