Monsoon in Southern Arizona: Essential Tips for Visitors (and Residents!)

If you’re planning a trip to Marana, your luggage most likely contains a combination of the following: swimsuit, hiking shoes, sunhat, and golf clubs.

But what about rain gear? Yes, rain gear! Although Southern Arizona boasts 350 days of sunshine annually, monsoon produces 54 percent (approximately 5.69 inches) of Southern Arizona’s annual rainfall.

Monsoon is the rainy season in the Southwest desert that occurs June 15 – September 30. The season results from a wind shift bringing tropical moisture up from Mexico, sparking widespread thunderstorms.

Thunderstorms are just the beginning! Some years fall short on rainfall, but an active monsoon may produce heavy rains, flash floods, lightning, dust storms, and microbursts.

These weather events can transform the parched desert into a verdant landscape overnight. Powerful storms can turn desolate river beds into roaring waterways. Giant trees and power lines become road obstacles. Lighting blazes through the sky like a flashing neon sign that reads, “Watch Me.” And most of us do.

Unless, of course, you’re 13 News First Alert Chief Meteorologist Erin Christiansen who is most likely tracking the storms from her weather center. Christiansen is a veteran broadcaster who has worked for 27 years in TV news and 20 years as a meteorologist. After spending 25 years in Tucson, Christiansen is a monsoon expert with extensive knowledge and stories to share.

"The thing I find interesting - 2020 was our second driest monsoon on record. Then 2021 was almost our second wettest on record. We literally had that huge swing from the second driest to almost the second wettest. But we ended up with the third wettest monsoon on record in 2021 and we were just 3/10 of an inch shy of our second wettest monsoon. To me that’s really pronounced you don’t normally go from one extreme like that to the absolute same level of extremity just one year later. I moved here in 97’ and I had never seen an about-face like that as far as monsoon extremes are concerned."

Here’s a look at some of the monsoon rainfall totals that broke records from the driest to the wettest:

The driest monsoons occurred:

1924 - 1.59 inches of rain

2020 - 1.62 inches of rain

The wettest monsoons occurred:

1964 - 13.84 inches of rain

1955 - 13.08 inches of rain

2021 - 12.79 inches of rain

“I remember the flooding in Sabino Canyon in 2006. I remember that it took 10 years to rebuild. After all, the flooding wiped out a lot of the trails in Sabino Canyon that were pretty pronounced. Heidi Schewel [with the Forest Service] took me through and I got to report on all of the damage. It was crazy to me. You hear OK - flooding run-off the trails are damaged. You’re thinking it’s not the world’s safest but it’s not the worst just some little gulleys that sort of thing. Then I got to actually see it. It was pure devastation. Rock slides and mud slides - to the point where I couldn’t even see the trails anymore"

“Any time you have heavy rain after a massive fire the flooding is going to happen so much faster… You get runoff. The soil is eroded. It also creates a harder surface, almost like a crust. That’s one of the reasons we flood so much because the soil is just so hard it’s like concrete. It doesn’t absorb water. We don’t have much for grass, trees or vegetation to absorb it. It’s like pouring water onto a table cloth and then tilting it. The incline of the mountains channels the water and speeds up the flooding. We're immediately going to get that runoff. On top of that, the Catalinas now have a huge area with a burn scar, where it’s kind of crusted and burned over with a lot of ash and it’s been baked almost (if you will). That doesn’t absorb any water either; it’s a recipe for flooding…

When I first moved out here in 1997 and probably for a good 10, maybe 15 years after I could almost set my watch by the time the storms would roll in every afternoon. It was like right around three, four o’clock you’d start to get the storms. We would have a huge downpour. The sun would quickly come out, we'd have some pretty rainbows. We'd have puddles, maybe some run-off in the washes and then you’d have to wait until the next afternoon for the rain to return. It was more consistent on a daily basis and so was the timing.

Monsoon is just not like that anymore. Now what we’re seeing is big breaks without any rain and without any storms. When we do get storms they usually are much more destructive.”