NEW YORK — Early Monday, hundreds of thousands of New York City parents looked outside to find the streets slushy and wet, but hardly impassable.

The problem? On Sunday night, Mayor Bill de Blasio had canceled school for Monday, warning of a potentially dangerous storm with up to 10 inches of snow.

In the morning, the decision immediately began to look like a miscalculation; 1.1 million students were home from their 1,800 schools for a few inches of slush. Even the city’s unreliable subways were running normally.

It is a fact of New York City politics that a mayor is only as popular as his most recent snow day decision. For decades, parents have scolded mayors for keeping schools open in big storms and closing them in small ones.

But de Blasio seems to be an especially popular target for parents’ anger.

In his five years in office, de Blasio has called seven snow days. In the decades between 1978 and 2013, there were only 11. Some parents praised former Mayor Michael Bloomberg’s reluctance to close schools, but he was also chastised and criticized.

Sensing the growing frustration — or perhaps taking note of his Twitter mentions — de Blasio defended himself on Twitter around 10 a.m., saying his administration opted to make “an early decision” so that working parents could plan ahead.

“For this mayor, the safety of our kids is the first and last question in the decision,” Eric F. Phillips, the mayor’s spokesman, said Monday.

“The mayor gets as much real-time expert forecasting as he can, he drills those running the buses and the plows, and he makes the call with as much time as possible for parents to plan. This is a no-win dynamic for any mayor.”

Phillips also noted that snowfall totals were higher in the Bronx and Upper Manhattan.

That wasn’t enough to placate frustrated New Yorkers.

When de Blasio made his decision Sunday night, meteorologists and city officials were predicting that the New York area could see as many as 10 inches of snow by 7 a.m. As the wintry mix began to fall with temperatures just above freezing, those estimates decreased.

Ultimately, while some areas around the city saw snowfall totals close to 1 foot, the National Weather Service reported that only 5 inches of snow fell overnight in Central Park, and totals were closer to 2 inches in parts of Brooklyn and Queens.

The decision to shutter the nation’s largest school system is a particularly unenviable choice any mayor must make.

On one hand, the city is loath to close schools because the vast majority of New York City public school students are low-income, and many working families cannot work from home or afford a baby sitter. With the city’s homeless student population at a record high, school can be the only place where vulnerable children get a hot meal all day.

But recent history shows just how ferocious the response can be when schools are left open in a bad storm.

When an unexpectedly messy snowstorm hit New York and New Jersey in November, some students with special needs were stranded on their school buses for 10 hours without food or access to a bathroom as snow and ice accumulated. Furious parents wondered why their children were not let out of school before the snow started falling.

The mayor was forced to apologize for his bungled handling of the storm, which likely influenced the decision to close schools Monday.

And just a few weeks after the mayor took office in 2014, the city was hit with nearly 1 foot of snow, and de Blasio kept schools open. He faced a torrent of criticism from everyone from the United Federation of Teachers president to Al Roker.

De Blasio’s then-schools chancellor, Carmen Fariña, defended their decision by declaring, “It’s a beautiful day.” The comment landed her days of unflattering coverage on the front pages of the city’s tabloids.

De Blasio was not the only local official who shuttered schools Monday. In New Jersey, where Gov. Philip D. Murphy declared a state of emergency, school districts began announcing closures or delayed openings as early as Sunday evening.

Schools in the cities of Hoboken, Secaucus and Jersey City, all just across the Hudson River from Manhattan, were all closed Monday. In suburban Bergen County, about 30 school districts opted to close for the day; roughly an equal number opted to open late. In adjacent Essex County, a handful of districts gave students a snow day, while schools in neighboring districts opened with a delayed start.

It was a patchwork approach — different schools in different districts doing different things — that caused confusion and consternation among parents weary of weather-related disruptions to their family’s routines.

Snow day decisions involve a complicated calculus of politics and logistics. New York City’s response to the most recent storm typically influences the next decision; if the mayor was seen as overly alarmist over just a few inches, he may be more hesitant to cancel schools, but if he took heat for mismanaging a storm, it is easier to make the case for an abundance of caution.

A morning snowstorm can be particularly tricky for schools because a massive fleet of yellow buses have to leave their depots, typically before the sun rises, and pick up tens of thousands of students. Those buses then interfere with the 1,600 snow plows the mayor said would comb the streets overnight. Heavy snow can effect subway service, and New Yorkers are familiar with city buses skidding and sliding across avenues in bad weather.

Then there is the question of unreliable forecasts: De Blasio defended his administration’s response to the November storm by noting that the forecast only called for 1 inch of snow, when 6 inches that fell during rush hour — an especially inconvenient time — paralyzed the city.

With the start of spring just a few weeks away, de Blasio was likely also betting that it would be the only snow day of the season. In the past, the city has been more hesitant to close schools early in the winter.

At a news conference Monday afternoon, de Blasio said that he and the schools chancellor had decided to close schools in order to protect children.

“It indicated the kind of situation that was going to hit right as the school buses were rolling, and potentially very intense accumulation around that time,” he said. “It just did not look like a safe situation for kids based on the information that we had.”

This article originally appeared in The New York Times.