Nationwide, fall temperatures have risen by about 3 degrees over the last five decades. They've jumped even higher across the Mountain West and Southwest, where fall is warming faster, according to a report by Climate Central, a policy-neutral nonprofit.
Since 1970, Reno, Nev., has warmed nearly 8 degrees – the most in the nation. Not far behind are Las Vegas and Phoenix (6 degrees) and Colorado Springs (5 degrees). Other Mountain West cities have seen average fall temperatures increase about 4 degrees, including Denver, Boise, Albuquerque, Salt Lake City, and Cheyenne.
That extra heat brings real challenges for people in the West, said Kaitlyn Trudeau, a researcher at Climate Central.
"Think about the increased cooling costs from air conditioning," she said. "Think about the health impacts, the wildfire season that's expanding. Warmer fall means a longer growing season, which means more allergies."
Trudeau said human-caused climate change is making fall heat far more likely and intense. She warns that if greenhouse gases keep rising, fall in the West may continue to feel more like an extended summer.
"We're just really seeing this expansion," she continued. "Summer's kind of being a bully, and expanding into the spring and into the fall and kind of taking over a huge chunk of our annual cycle."
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Colorado and KANW in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
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