City educators — and their unions — are not happy about the Department of Education’s decision to keep schools  open today in the face of an approaching winter storm.

Chancellor Carmen Fariña announced last night, long before the first flakes fell, that schools would be open today. If stores and workplaces are open, schools should be too, she said, as she has before. (We put together a more complete accounting of Fariña’s rationale for keeping schools open whenever possible last week, the last time weather conditions might have merited a snow day.)

But as blizzard-like conditions snarled morning commutes today, keeping students and educators alike from getting to their schools, Fariña’s decision drew sharp criticism.

“I understand the desire to keep schools open. The only thing that trumps that is safety,” teachers union president Michael Mulgrew said in a statement. “It was a mistake to open schools today.”

The city’s announcement on Facebook that schools would be open drew more than a thousand critical comments. Some even called for the return of former mayor Michael Bloomberg, who himself was known for being stingy with snow days and for making the call about whether to keep schools open in the morning, after some teachers had left for work.

But on the teachers union’s Facebook announcement, much of the criticism was reserved for the union itself. Members said they were tired of using their personal days to stay home because of bad commutes or because their children’s suburban districts had called classes off.

“When does our union step in and actually try to do something about this?” asked Danielle O’Keeffe. “This is a major safety issue. If my child’s school is closed because it’s too dangerous to travel down the block then why is it not dangerous for me to travel 25 miles?”

A spokeswoman for the city’s principals union, the Council of School Supervisors and Administrators, suggested that the Department of Education could do more for educators, who have not gotten the same dispensation to skip school in city press releases that families have.

“In recognition of how terrible the travel conditions are, DOE should institute an appeals process for those members who could not get in today (as it did for Hurricane Sandy) and award compensatory time,” said the spokeswoman, Chiara Coletti.

The union’s president, Ernest Logan, echoed Mulgrew in saying that Fariña had made the wrong call.

“The decision to open or close schools during severe storms is not a simple one, but today’s decision should have been simpler than most,” Logan said in a statement.” If ever there was a day to set aside bureaucratic concerns, today was the day.”