Rain in the Desert

Monsoon Season

Rain may be the furthest thing from your mind when you plan your trip to the desert southwest. But late-summer visitors to red-rock country quickly learn that they should expect the unexpected during “monsoon season.” A typical August day will start out innocently enough. Blue skies and sunshine are generally all you will see before late afternoon. But gradually, billowy white clouds begin to form as the intense desert heat pushes moist air high into the atmosphere. Frequently, those puffy clouds become black and ominous, and a feeling of anticipation begins to build.

Late afternoon thunderhead over Zion.
Late afternoon thunderhead in Zion Canyon, Utah.

Raging Rivers

Precisely when and where a storm will hit is almost impossible to predict. The threat of rain occurs much more often than actual precipitation. But almost daily, somewhere between Phoenix, Las Vegas, and Moab Utah, a sudden, violent storm will transform dry ravines into raging rivers, bring house-sized boulders down from their precarious perches, and carve narrow canyons a little deeper, pushing millions of tons of sediment seaward.

What to do during the rain?

Does this mean you should cancel your travel plans? Does it mean you should postpone your trip for later in the year? No, but there are a several things you’ll want to be aware of to make sure you aren’t caught unprepared:

  1. Bring your camera! Some of the most dramatic photo opportunities you will ever get will be during the monsoon season in the desert southwest. Waterfalls, rainbows, and spectacular lighting effects are common from the last part of July through mid September.
  2. Don’t go out without a weather report and rain gear. You might think that getting wet will simply cool you off on a hot summer day, but few things can make you more miserable than getting thoroughly soaked as temperatures drop and wind blows during and after a storm.
  3. Avoid camping in low spots such as dry river beds or beneath overhanging cliffs where debris could fall on top of you. Look around. Do you see rock falls and boulders nearby? Where do you think they came from? Do you see black vertical streaks (“desert varnish) on the sides of cliffs? Those result from intermittent waterfalls which flow more frequently than you realize.
  4. Avoid narrow slot canyons which offer no “high-ground” in the event of a flood, or high spots which would be a target for lightening. Best to be somewhere between the highest and lowest point in the area.

Monsoon season on the Colorado Plateau (the large red-rock region in the four-corner states of Utah, Arizona, Colorado and New Mexico) and the surrounding area is an exciting, dynamic and often spectacular time of year to visit. Just don’t be surprised if blue skies quickly turn a hot summer day into a dramatic display of natures fury.

Temporary waterfall in Zion Canyon after a summer rainstorm.
Temporary waterfall in Zion Canyon.
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