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New Heat Study Reveals Fort Collins Headed for Increased Heat Waves

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Fort Collins experienced two times as many 90-degree days in the past 14 years than in the previous 39 years, a wakeup call for how the City will need to adapt to a changing climate, according to a new report prepared for the City by the Rocky Mountain Climate Organization.

The City commissioned the study to analyze climate model predictions for future heat impacts in Fort Collins specifically.

“The City is already engaged in evaluating risk and vulnerability to the provision of City services and infrastructure from a changing climate. The information contained in this unique report will help the City plan for and prioritize actions to minimize the impacts of predicted heat increases,” said Lucinda Smith, director of the Environmental Services department.

According to the National Weather Service, extreme heat killed more Americans in the last decade than any other weather-related event. Other impacts from increased heat include impacts to water quality and quantity, elevated wildfire risk, worsening air quality, and increased energy use for cooling purposes.

Earlier this year, the National Oceanic and Atmospheric Administration revealed 2013 as the fourth hottest year ever recorded. The year 2012 was the hottest on record nationally and in Fort Collins.

The Rocky Mountain Climate Organization report relied on data from the Colorado State University weather station to assess Fort Collins’ historic heat events and predict future heat events under two climate model scenarios – one with a lower level of future emissions from heat-trapping greenhouse gases and one with a medium-high level. Heat events are defined as non-overlapping occurrences of three consecutive days of temperatures above a threshold.

“This illustrates what Fort Collins has at stake as humans change the climate and why Fort Collins' award-winning leadership in reducing climate-changing pollution matters," said Stephen Saunders, president of the Rocky Mountain Climate Organization and the report’s lead author.

The study, which examined 1961 to the present, revealed:

  • Fort Collins averaged 18 days/year of 90 degrees or more between 1961-1999. Yet in the first 13 years of this century, the City averaged 34 days/year of 90 degrees or more, nearly twice as many.
  • Hot stretches of three straight days of 90 degrees or hotter have occurred 2.6 times more often between 2000 and 2013 than they averaged between 1961 and 1999.
  • In the first years of the 21st century, Fort Collins has averaged three times as many 95-degree days as in the last 39 years of the 20th century.
  • 95-degree single days and heat waves have gone up at higher rates than those 90 degrees and hotter between 2000 and 2013 than in the last 39 years of the 20th century.
  • The predicted frequency of single, 95-degree days could be 3.5 times higher (compared with 1961–1999) by mid-century under a lower emission scenario, or about 5.9 times higher if future emission rise at a medium-high rate.

The report also reiterates that the state’s most destructive wildfires in the past several years started on extremely hot days: The High Park fire west of Fort Collins, for example, started on a day that had a high temperature of 93 degrees.

“We have worked hard to maintain accurate historic climate data for Fort Collins,” said Nolan Doesken, state climatologist and senior research scientist at Colorado State University’s prestigious Department of Atmospheric Science. “We realize the warming described in this report is a combination of local warming resulting from the growth and urbanization of what was once just a small rural community along with regional warming affecting much of Colorado in the past few decades. The higher frequency of very hot temperatures is indicative of what we all may be dealing with more often in the near future. I appreciate that our City is thinking about potential future consequences from heat, drought, wildfire and floods and being proactive today.”

The CSU weather station is one of 24 NOAA-designated stations in Colorado included in the U.S. Historical Climatology Network to help with the detection of climate change.

Fort Collins has long been committed to reducing local greenhouse gas emissions, and will be updating its Climate Action Plan this year. The report underscores how the predicted heat increases are lower under a lower emission future. In November, President Barack Obama appointed Fort Collins Mayor Karen Weitkunat to a Task Force on Climate Preparedness and Resilience. The 26-member task force will advise the President on how best to prepare communities for the impacts of climate change. For more information on the City’s efforts, go to

The Rocky Mountain Climate Organization is a Colorado-based non-profit organization made up of local governments and government agencies, non-profit organizations and businesses united to bring about climate understanding and action. Among its partners are the Cities of Fort Collins, Boulder, Denver, Aurora, Aspen, Breckenridge, Frisco and Vail. For more information, go to