Discover the June Heatwave That Turned Colorado Into a Fiery Oven

Written by Patrick Sather
Updated: July 28, 2023
© leolintang/
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According to the National Weather Service, June 2012 ranked as the worst June heatwave in Colorado’s history. From 1981 to 2010, Colorado recorded a mean temperature of 67 degrees during the month of June. However, in June 2012, the mean temperature equaled 75 degrees, nearly 8 degrees above the average. 

From June 9 through June 26, 2012, Colorado recorded numerous days with heat in the high 90s and low 100s. On June 25, temperatures in Denver climbed as high as 105 degrees Fahrenheit, the hottest temperature ever recorded in the city. Due to the persistent heatwave, Denver set 8 new daily high-temperature records over the course of June. Meanwhile, Las Animas – one of the warmest cities in Colorado – recorded its highest temperature ever on June 24, 2012, when the temperature reached a scalding 114 degrees Fahrenheit.  

Let’s take a deeper look at the history of heatwaves in Colorado. We’ll also explore the causes behind the June 2012 heatwave, and the effects it had on people, the economy, and wildlife. 

Notable Heatwaves in Colorado

While not as prominent as in some other states, June heatwaves occur periodically in Colorado. Here’s a list of notable heatwaves in Colorado history:

  • 1936 – The 1936 North American heat waves ranked as one of the worst in Colorado’s history. Several cities in Colorado recorded temperatures as high as 100 degrees Fahrenheit over several days in June. The heatwave claimed over 5,000 lives across the United States and Canada and led to massive crop failure. 
  • 1980 – The 1980 United States heatwave caused incredible devastation across the Midwest and Southern Plains. At least 1,700 people lost their lives, and damage to agriculture exceeded $20 billion. In June of 1980, the average daily temperature exceeded 73 degrees, well above normal for that time of year. 
  • 2006 – Another sizeable heatwave hit Colorado in the summer of 2006. Temperatures climbed into the 90s for several days in June, making 2006 one of the 10 hottest years in Colorado since 1881. Over the whole of North America, the 2006 heatwave led to at least 225 deaths. 
  • 2011 – Coloradans got more than their fair share of heat during the early 2010s. In 2011, temperatures reached 97 degrees Fahrenheit in Colorado Springs by early June. Meanwhile, Denver saw highs of 104 degrees Fahrenheit on June 19, while Pueblo hit 101 degrees Fahrenheit. 

Causes of the 2012 Heatwave

Heatwave hot sun. Climate Change. Global Warming. Thermometer high temperatures.
Heatwaves are caused by high-pressure domes that trap hot air in place.

©Ed Connor/

The 2012 North American heatwave was caused by a high-pressure dome of hot air. The dome originally formed over Baja California, Mexico, then strengthened and moved east across the United States and Canada

Numerous factors work together to create a heatwave. Under normal conditions, cool air sinks toward the surface while hot air rises. Sometimes, the air gets trapped due to a lack of prevailing winds. These winds normally circle the globe, mixing the air and preventing long-term hot or cold air accumulations. However, certain factors can trap wind, creating the conditions for a heatwave. 

When exposed to high pressure, hot air sinks toward the surface. This creates a dome of hot air, preventing the heat from escaping into the atmosphere. The absence of lift prevents the formation of convective clouds, which stifles rainfall. Over time, the heat builds up, leading to drought and high temperatures. 

Impacts on People

Woman protect herself from the hot sun while walks in a downtown street during an extreme heatwave in Sao Paulo, Brazil.
The June 2012 heatwave claimed at least 123 lives across the United States and Canada.

©Nelson Antoine/

The 2012 June heatwave significantly impacted people living in Colorado. 

Health Risks

The CDC recognizes extreme heat as the leading cause of weather-related death in the United States. From 2004 to 2018, around 700 people per year died in the United States due to extreme heat. In years with strong heatwaves, this number can climb exponentially.  

The 2012 North American heatwave lasted for just over a month, from mid-June to late July. However, during that short time, the heatwave claimed the lives of approximately 123 people. People most at risk included the elderly, very young, and people with developmental or cognitive disabilities. High temperatures increase the risk of heatstroke as well as heat-related health issues such as heart attacks and strokes. 

Water Shortages

At the start of 2012, Colorado was already dealing with drought across 50% of the state. The 2011 drought in the American Southwest had caused dry conditions throughout the Rio Grande and Arkansas river basins in Colorado as well as reduced snowfall in the mountains. 

By the start of the 2012 June heatwave, Colorado authorities reported drought-like conditions throughout the entire state. Reduced snowpack in the mountains led to low water levels in rivers. Nearly 80% of Colorado’s water supply comes from mountain runoff. The lack of runoff in 2012 led to severe water shortages. This forced authorities in certain districts to claim temporary water rights to divert water from several reservoirs across the state.  

Impacts on the Economy

The National Oceanic and Atmospheric Administration’s National Climatic Data Center keeps track of the costs associated with natural disasters in the United States. While hurricanes top the list of most costly disasters, heatwaves rank as a close second. 

To date, the 2012 North American heatwave ranks as the 2nd-costliest heatwave in U.S. history. The heatwave caused more than $30 billion in damages across the country. 

The heatwave hit the agricultural, tourism, and recreational industries hard in Colorado. Hay prices doubled or tripled in certain areas as production plummeted. State authorities estimate that almost 100,000 planting acres failed, while another 120,000 acres experienced conditions that prevented planting. Meanwhile, low water levels impacted the white-water rafting industry, which led to a 15% decrease in revenue compared to 2011, from $151 million to $127 million. Similarly, the skiing industry reported a drop in visitation of nearly 12% compared to the 5-year average. 

Impacts on Wildlife

Residential community after Waldo Canyon Fire 2012 in Colorado Springs, Colorado.
The Waldo Canyon fire burnt through thousands of acres of forest and destroyed hundreds of homes.

©Arina P Habich/

The June 2012 heatwave not only killed people and hurt the economy but also caused devastation for ecosystems and wildlife across the U.S. Persistent high heat and drought conditions created the perfect conditions for wildfires. 

In Colorado, the Waldo Canyon fire caused widespread devastation in the Colorado Springs area. The fire started on June 23rd and was not fully contained until July 10, 2012. The fire burned through the Pike National Forest and burned an area of approximately 18,247 acres. 

What We Learned From the 2012 Heatwave

June 2012 saw the worst June heatwave in Colorado’s history. While the 2012 heatwave caused significant environmental and economic damage, it did not cause the same loss of life as some earlier heatwaves, such as the 1936, 1980, or 2006 heatwaves. Thankfully, lessons learned from earlier heatwaves prevented a more substantial loss of life. 

Still, the heatwave exposed a number of critical issues and vulnerabilities. Namely, the heatwave highlighted the dangers of drought. Climate change is increasing the incidence of heatwaves, which in turn is making droughts longer and more intense. This, in turn, impacts food security and water supplies, which impact both people and the environment.  

The 2012 heatwave demonstrated to Coloradans the importance of having emergency water storage and water rights policies in place to combat drought. With these procedures in place, Colorado farmers and ranchers can react more quickly to prevent the loss of crops and planting delays. 

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