At least 5 inches of snow was forecast for an area from Cheyenne, Wyo., to Denver Wednesday just days after temperatures in the 70s were recorded, CNN reported.
More than 6 inches of snow accumulated in Cheyenne through early Wednesday, AccuWeather.com reported.
Forecasters said snow could create slushy and difficult travel conditions along stretches of Interstates 25, 70 and 80 in the region.
After topping out at 80 degrees Monday, temperatures were in the 30s across the Denver area early Wednesday, AccuWeather.com said.
"If everything comes together, the mountains to the west of Denver could receive a foot or more of snow on Wednesday," AccuWeather.com Meteorologist Erik Pindrock said. "Denver averages about 1.3 inches of snow during the month of May, which means that snowfall this time of year isn't rare."
The typical last day for snow for Denver is April 26, but the record for the latest snowfall is June 12, 1947, the National Weather Service said.
A May snowstorm is expected to deliver moderate-to-heavy accumulations of snow through Thursday in parts of Minnesota and Wisconsin, the National Weather Service said. Totals of 6-9 inches of snow were forecast.
Meanwhile, temperatures hovering around 100 degrees F for the last few days in the Phoenix area will be in the mid-90s Wednesday, CNN said.
After similar temperatures Wednesday in New Mexico and western Texas, forecasters said the area will see daytime temperatures plunge to the 50s Thursday.