Monsoon Season In Las Vegas

If you visit Las Vegas from July through September, you’ll probably hear the term “monsoon season” in local weather forecasts. Since Las Vegas receives only about four and a half inches of rain annually, the term may not make sense at first, but if you’ve ever witnessed a flash flood in progress, it’s easy to see how the misplaced label stuck.

During Vegas’ monsoon season, moisture from the Gulf of Mexico moves in, often developing into billowing thunderheads in the afternoons. Humidity rises, and the temperature may drop–if the temps are high, the extra humidity is like adding the proverbial insult to injury. Most of the time, the ominous-looking afternoon clouds do nothing more than sputter just enough moisture to dirty your windshield. But sometimes they show off with thunder, lightning, and downpours—and sometimes they bring flash floods. Residents and visitors can be caught off-guard by the fast-moving waters of a flash flood: one minute there’s a trickle of water coming down the street, and the next minute it’s rushing over the top of your tires.  The National Weather Services advises drivers not to try driving through flood waters—if you can’t tell how deep the water is, or if a street is barricaded, take an alternate route.

This time of year, be especially alert to the weather if you’re hiking in the desert around Las Vegas, or in any part of the Southwestern United States. In July, three Las Vegas hikers in Zion National Park were swept away in a flash flood after an inch of rain fell in less than 30 minutes. Keep an eye on the clouds, stay out of the washes (what the locals call riverbeds that fill with water when it rains), and be cautious in narrow canyons. And be sure to have your camera handy—the monsoon season’s towering clouds (technically, they’re cumulonimbus) look stunning in pictures.

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Picture of cloudy Strip courtesy of Britta Heise

Photo of thunderheads over the desert courtesy of Bryce Bradford