Colorado Weather: Roasting Yesterday, Snowing Today

BOULDER, Colo. — Wait, what happened to fall?

On Monday, the region around Denver was sweltering in summer heat, the scorched skies thick with haze, smoke and ash from a wildfire

roaring through the dried-out forests near Rocky Mountain National Park. By Tuesday morning, there was snow on the ground, and temperatures had plunged more than 50 degrees Fahrenheit.

“We switched from summer to winter in a day,” said David Barjenbruch, a senior forecaster at the National Weather Service in Boulder.

Outside his office, an inch or so of snow was already sticking to hillsides and tree branches on Tuesday morning, the start of what was expected to be a daylong snowstorm, dropping more than 12 inches in the foothills and mountains and three to six inches around Denver.

Mr. Barjenbruch said the cold air mass had rolled in from above the Arctic Circle, traveling rapidly south along the spine of the Rocky Mountains. Some of Colorado’s ski resorts, which have been preparing for a socially distanced ski season, were expected to get an early dump, though probably not enough to last until they open around Thanksgiving. Live cameras showed that mountain passes were already a blur of white.