The North American Monsoon

August 29, 2023
3-5 minutes


The word monsoon originates from the Arabic word “mausim,” meaning season; so — while torrential downpours in deep jungles and tropical destinations might be the first idea our mind conjures when we think of monsoons — the term monsoon can actually be used to refer to any seasonal weather change. The North American monsoons that occur in the southwest United States are one example of a monsoon that exists outside of the traditional definition of this weather phenomenon and serves as an interesting example of how monsoons play a role in the larger picture of global climate.

What is a Monsoon?

At its simplest, a monsoon refers to changes in the atmospheric patterns of an area — most notably changes in the wind and precipitation conditions of a region. Monsoon season begins with minor shifts in weather patterns  —  this includes changes in windspeed, temperature, or moisture. As these small changes begin to interact with one another, their effects are exacerbated: leading to a full-blown monsoon.

Monsoons most often occur in the summer because of the weather patterns of the season. During the hotter months of the year, heat from the sun warms the air over land. Later, cool moist air from the ocean blows over this land. The hot temperatures cause this moist air begins to rise and condense — becoming monsoon rain.

Understanding the North American Monsoon

In the United States, the summers of the southwest are exceptionally hot. Because of this heat, a region of high pressure can build over the continental landmass. This redirects wind across the continent — pulling the moist air from the pacific ocean towards the southwest and causing monsoons. These monsoons begin to develop in June and July and typically end around mid-September.

The North American monsoon differs from its counterparts in Asia because instead of presenting a constant flow of rain, these storms have a diurnal cycle. This means that they flow in patterns of dry mornings, followed by wet and rainy afternoons. However, while the monsoons of the American Southwest and the monsoons of Asia or Oceania may seem distinctly regional because of their differences, monsoons are a result of larger global circulation and wind patterns.

Why is the North American Monsoon Important?

The Southwest United States (mainly New Mexico, Texas, and Arizona) receives between 75 and 50 percent of its total annual rainfall during the short monsoon season that occurs each year. These rains are essential to the desert ecosystem, allowing plant and animal life to continue to thrive in the usually inhospitable environment. This rain is also important in cooling down the scorching summer temperatures — that regularly surpass 100°F (38°C) — helping to reduce the number of those affected by heatstroke, sunburn, and other heat-related health issues.

What are the Dangers of the North American Monsoon?

Despite the many advantages that the monsoons of the southwest United States may bring to the region, there is a plethora of dangers that arise as well. Wind from monsoons can cause dust storms, increased rain will often lead to landslides, and lightning can set fire to the desert landscape. Additionally, because the region experiences so little rain during the majority of the year, populations are generally unequipped for potential monsoons.

Climate Change and the North American Monsoon.

Climate Change is making monsoons more unpredictable. Scientists foresee scenarios where climate change causes the monsoons of the American Southwest to come later or earlier in the year, or with more or less intensity than they have historically. This future unpredictability will likely cause increased danger to populations around the area.

The most likely future monsoon scenario includes storms occurring later in the year, less frequently, and with more intensity. This means that land with be further dried out when rains come, and monsoons will be more destructive. Intense storms will likely result in flooding, road closures, and infrastructure loss.

The 2022 North American Monsoon

The 2022 North American Monsoons saw that — as the rest of the nation experienced record-breaking heat — the southwest was able to keep cool and wet. The region was 30 to 40 percent cooler than normal and experienced 40 to 50 percent more rain. This rain helped to bring moisture to the area and helped to ameliorate some of the effects of the ongoing drought in the region. The 2023 monsoon season has already been shown starting later than usual, a nod to the fact that climate change may be affecting weather patterns.