A snowday chance calculator helps Ontario families estimate the likelihood of school closures based on forecast snowfall, temperature, and storm conditions. For Canadian parents who need to plan childcare, remote work, and school bus schedules, having an early estimate of snow day probability is genuinely valuable. How Ontario School Boards Make Snow Day Decisions: Ontario major school boards follow similar decision frameworks that weigh multiple factors simultaneously. The Toronto District School Board, Durham District School Board, Peel District School Board, and others begin assessing weather conditions the evening before and make final decisions between approximately 5:00 AM and 6:30 AM. Key factors include total accumulated snowfall by morning, road and sidewalk conditions from board maintenance staff, active Environment Canada weather advisories, wind chill severity, school bus contractor route safety assessments, and municipal transit service status. The Role of Environment Canada Warnings: Environment Canada weather warning system provides the official framework Ontario school boards reference when making snow day decisions. Special Weather Statements are issued for accumulations of 10 to 14 centimetres. Snow Warnings apply to accumulations of 15 centimetres or more. Winter Storm Warnings combine significant snowfall with reduced visibility and dangerous wind chills. When an active Snow Warning or Winter Storm Warning is in effect during overnight and morning hours, the probability of school closures increases substantially. Freezing Rain and Ice Storms in Ontario: Freezing rain events often trigger closures at lower precipitation accumulations than snowfall because icy surfaces are more hazardous to pedestrians and school buses. A 5 to 10 millimetre freezing rain event frequently triggers school closures even though the precipitation total is much lower than a typical snow day threshold. Preparing for Ontario Winter Weather Events: Keep your school board website bookmarked and set up email alerts through the board parent portal. Most Ontario boards provide automated calling systems or app notifications to registered families. For official storm morning decisions, always check your school board website directly after 6:00 AM rather than relying on social media or third-party sources. For the most reliable snow day information in Ontario, combine this probability estimate with direct monitoring of your school board website and automated notification system. Most Ontario school boards send email or text notifications to registered families between 5:30 AM and 6:30 AM on storm mornings when closures are confirmed, giving parents adequate time to arrange alternative childcare or activate remote work arrangements before the standard workday begins.