It's a decision that sparks joy for some but chaos for others: Calling a snow day.

Parents across Canada have been forced to scramble in recent weeks as wintry conditions have prompted schools to shut, with some regions recording an unusually high number of closures.

"The school closures have been a nightmare this winter," says Magdalena Castelli, who has three children in southern Ontario's Hamilton Wentworth District School Board and another in daycare.

The disruption to daily routine can unleash a pre-dawn scramble in households, a juggling act that sees some parents work from home, drop kids at a babysitter's place or trudge into the office with charges in tow.

"When they close a school, they don't see the big impact that has on people's lives," says Castelli.

Watch the impact major winter storms have on Canadians across the country:

Some of Canada's biggest cities are all but shut down as major winter storms bring extreme cold, freezing rain, snow, and wind. Depending on where you are and who you ask, it's either a blessing or a cruel punishment. 2:59

Student safety is consistently cited as the driving force behind snow days, but the wide variety of policies in different parts of the country demonstrate the subjective nature of those decisions.

An examination reveals a haphazard patchwork of varying approaches to inclement weather across Canada that appear to be based on a region's common practice and culture as much as the forecast.

While schools in the prairie provinces virtually never close for bad weather, ones on Canada's East Coast regularly shut down during snowstorms.

In B.C., Ontario and Quebec, schools tend to call snow days sparingly.

Atlantic Canada leads the way in snow days

The snow-day disparity cannot entirely be explained by weather, suggests Linda Libby, a meteorologist with Environment Canada.

"It's different across the country," she said. "I don't use the term worse."

Atlantic Canada is on multiple storm tracks and temperatures can often hover around the freezing mark, but Libby said "it doesn't mean our weather is any worse."

Some school boards in Atlantic Canada consistently report double-digit school closures over a winter. (Darren Calabrese/Canadian Press)

Still, the number of snow days remains higher in the Maritimes, with some school boards consistently reporting double-digit closures over a winter.

Halifax tends to have fewer snow days than more rural areas, averaging about 4.4 days a year over the last decade.

But that's still more than double the number of school closures in similar-sized cities in Quebec and Ontario. For example, Quebec City averages 1.75 snow days a year, while the Hamilton area averages 1.6 days — though this year, it has had substantially more.

Rare in the Prairies

The contrast between Atlantic Canada and the prairie provinces is even more dramatic.

When asked about the number of snow days for the last 10 years, a spokesperson for Edmonton Public Schools said: "Zero."

A response from the Winnipeg School Division was similar.

"We have not had a 'snow day' in over 30 years," spokesperson Radean Carter said. "Our policy — and this applies for all school divisions in Winnipeg — is that schools remain open unless city buses are shut down."

An Edmonton Public Schools spokesperson said there have been 'zero' snow days over the last 10 years. (Dave Bajer/CBC)

Schools in Saskatchewan also rarely close — if ever.

For example, Regina Public Schools, the Regina-based administrator for the city's schools, doesn't have snow days, said spokesperson Terry Lazarou.

"Our schools will remain open through most weather-related occurrences, including snow or –40 C temperatures," he said.

Lazarou said there have been multiple times in the past several years that school buses didn't run because of extreme snowfall or ice accumulation.

"But schools did not close because of it," he said. "We do not keep records of schools closing due to weather because it does not happen."

A report on school storm days in Nova Scotia in 2009 acknowledged the role of culture in snow-day decisions.

"Two closely connected practices have become a long-held tradition in the public school culture in Nova Scotia," the report said. "Schools are closed to students when the buses are cancelled because of the weather and ... teachers do not have to report to work on storm days when schools are closed to students."

Variance within cities

In Ontario, the Durham District School Board, which includes Whitby, Oshawa and surrounding communities, remains open even when buses are cancelled due to inclement weather.

"We still have a lot of students who are within walking distance — all the students in the immediate surrounding neighbourhood would walk to school," said Christine Nancekivell, chief facilities officer for the Durham board.

"Even bus students, some parents would still drive them to school and drop them off. So there are still students that attend, and school is still open."

Even within the same city, different schools boards can take different approaches. (Peter Power/Canadian Press)

But different school boards can take different approaches. For example, the Hamilton Wentworth District School Board says if bus transportation is cancelled, schools are closed.

Yet the Catholic school board in the same region does not have the same policy — it cancelled bus service this week but schools remained open.

The arbitrary nature of snow days across the country has some parents speaking out about the frustration of dealing with school cancellations and the potential impact on instructional time.

New Brunswick's education minister has spoken out about the loss of classroom time in the province.

Watch how snow days are decided in New Brunswick:

This is what happens behind the scenes when transportation managers see snow, ice or other trouble in the forecast. 1:48

Dominic Cardy has floated the idea of so-called blizzard bags — homework for students to do on a snow day.

Nova Scotia Teachers Union president Paul Wozney said teachers already provide students with learning activities with a take-home component.

He said preparing multiple baggies for kids to use on storm days is a "staggering amount of effort" given that type of time away from the classroom doesn't hurt learning.

Wozney pointed to a 2014 study by Harvard University researcher Joshua Goodman that found a strong relationship between student absences and achievement, but no impact from lost instructional time due to school closures.

Besides, he said, any stereotype that teachers are "at home drinking scotch in their jammies" couldn't be further from the truth.

Watch as people in Ottawa get creative with their commute:

People in Ottawa got creative with their commute on Wednesday, after the city got about 30 centimetres of snow in under 24 hours. The CBC's Matthew Kupfer tried his hand at snowshoeing to work as part of a winter commute triathalon. 0:57

He said teachers use snow days to catch up on marking, communicate with parents, work on lesson preparation, develop individual program plans and for personal wellness.

"Teachers are burning out at epic rates, so some are going to self care," he said.

'This isn't 1945'

Yet many parents are also under pressure, and snow days can add to the stress.

"Whatever the weather, we need to get to work," says Castelli, the mother of four in the Hamilton region, noting some parents must go to work to get paid and be able to feed their children.

Cardy says he has heard concerns from parents about the scramble for last-minute child care.

"This isn't 1945. You don't have a parent at home baking cookies for the kids while dad goes off to work," Cardy said. "It's a totally different society and we haven't done a lot to recognize the changes."

He said snow days could unfairly disadvantage low-income earners, who may have to take an unpaid day off work or pay for additional child care on an already stretched budget.