Passengers at the station were "stomping around trying to keep warm" while awaiting their ride to work, he said.
Frustrated Metra customers have taken to social media to vent their ire. One Twitter site, @OnTheMetra, "celebrates the endless list of #MetraFail."
Metra Deputy Executive Director Pete Zwolfer said Tuesday that contrary to what some customers may have thought, Metra had been making preparations for the extreme weather since Friday.
"We knew we were getting the cold, and we knew we were getting some snow," Zwolfer said. "But when we started getting a foot (of snow) dumped on us, it made things worse."
Metra started running into problems with staffing on Monday when crew members began reaching their federally decreed limit on hours, Zwolfer said.
Many crews, for example, normally work both morning and evening runs, with a mandatory four-hour rest break in between, Zwolfer explained.
But if morning trains are delayed, then the rest break gets pushed back, disrupting evening schedules. And if evening trains run late, crews may not be able to get the required eight hours of rest before the start of their next shift, he said.
Most of the time, there are enough backup crew members to fill in, but the roll of these extra workers was quickly exhausted in this case, Zwolfer said.
A 30-year Metra veteran, Zwolfer said this week's double whammy of cold and snow ranks in the top five weather woes he's experienced, with perhaps the worst being a March 1998 ice storm.
After Monday's incident on the UP Northwest Line, Metra conferred with Union Pacific officials, who took responsibility for unloading the passengers at Clybourn, Zwolfer said.
The railroad is working "to make sure it doesn't happen again," he said.
Chicago is not alone in dealing with weather-related problems. Transit officials in other major cities also find it challenging to keep trains running on time in the bitter cold.
"You call people at (New York commuter lines) Metro-North or Long Island Rail Road, they'll tell you that they work hard to keep things running but sometimes conditions make it very difficult," said Robert Paaswell, the former head of the Chicago Transit Authority who now serves as a distinguished professor of civil engineering at City College of New York.
And frozen switches are not unique to Chicago, officials said. New York's Metropolitan Transportation Authority, which oversees two commuter lines and the subway, brings on extra workers to monitor critical switches and signals during major snowstorms and keep them free of snow and ice.
"I can certainly confirm that keeping switches warm is a major priority for us in New York during any winter storm," said Aaron Donovan, spokesman for the agency. "In the past couple of days, with the snow and the cold snap, we've had scattered problems with signals and switches."
Tribune reporter Mitch Smith contributed.