There’s no national rule for what temperature schools close at. The call is local, but most districts start seriously weighing a closure when wind chill drops into the -20°F to -35°F range, or when indoor classroom temperatures climb into the mid-80s°F. Geography, building condition, and how kids get to school all shift where a given district draws the line.
Cold Weather Thresholds
Wind chill does more of the work than the thermometer reading. A calm 5°F morning is uncomfortable but workable. The same 5°F with 15 mph winds produces a wind chill of -19°F, and exposed skin can freeze in about 30 minutes under those conditions.1National Weather Service. Wind Chill Brochure Districts that publish their criteria almost always lean on wind chill as the primary trigger.
The most common closure range sits between -25°F and -35°F wind chill. Districts in historically colder regions sometimes push the threshold lower. At -35°F wind chill, frostbite can develop on exposed cheeks, noses, and fingers in roughly 10 minutes, which is about how long many children spend waiting at a bus stop. The National Weather Service wind chill chart divides frostbite risk into three zones: 30 minutes, 10 minutes, and 5 minutes of exposure.2National Weather Service. Wind Chill Chart Policies anchored to those zones give a district something concrete to point to.
Some districts also set a straight-temperature floor regardless of wind. A sustained -15°F or colder during the morning commute is a common trigger. Extreme cold creates mechanical problems that force the decision whether anyone wants to make it: diesel fuel in school buses can gel between 10°F and 15°F, and lithium-ion batteries in electric buses won’t accept a charge below 32°F. A fleet that can’t start can’t run routes.
Hot Weather Thresholds
Heat closures are less standardized than cold ones, largely because many school buildings were never designed around air conditioning. In buildings without working AC, indoor temperatures can climb past outdoor readings surprisingly fast once classrooms fill with students and electronics.
The EPA, referencing ASHRAE comfort standards, recommends summer classroom temperatures between 73°F and 80°F depending on humidity.3US EPA. Reference Guide for Indoor Air Quality in Schools OSHA recommends workplace temperatures between 68°F and 76°F but does not legally require employers to provide air conditioning.4Occupational Safety and Health Administration. What Can I Do if My Indoor Workplace Is Too Hot or Cold? These are comfort guidelines, not closure triggers, but they mark the point where conditions start degrading.
A few states have begun setting hard indoor limits by law. At least one state now requires schools to begin a cooling protocol when an occupied room reaches 82°F, which can include turning off overhead lights, lowering shades, running fans, and providing water breaks. If a room hits 88°F, students and staff must be relocated to a cooler space. Those requirements took effect in September 2025. Extreme heat is particularly dangerous for younger children, who regulate body temperature less efficiently than adults and may not recognize early signs of heat exhaustion.
What Else Goes Into the Call
Temperature alone rarely drives a closure. Superintendents weigh a cluster of conditions that, together, make the school day unsafe.
- Road and sidewalk conditions. Heavy snowfall, freezing rain, and ice accumulation can make bus routes impassable and walking paths treacherous at moderate temperatures. A 28°F day with an ice storm is more dangerous than a -10°F day with clear roads.
- Power outages. Schools without electricity lose heating, cooling, lighting, and often water pressure. A building that can’t hold a safe indoor temperature is uninhabitable regardless of what’s happening outside.
- Air quality. Wildfire smoke, industrial incidents, and high ozone days can trigger closures or push all activities indoors. Some districts tie their call to the EPA Air Quality Index, closing or restricting outdoor activity when it crosses into “unhealthy” territory.
- Visibility. Dense fog, blowing snow, and dust storms that drop visibility below safe driving thresholds affect both bus routes and parent drop-off traffic.
Moderate cold plus icy roads plus a worsening forecast creates a different risk profile than bitter cold with sunshine and dry pavement.
Who Decides and When
The superintendent almost always holds final authority over weather closures. In practice, that call gets made between roughly 4:00 and 5:30 a.m. after a round of consultations that usually started the night before. Transportation directors assess road conditions and fleet readiness, facilities managers confirm building systems are running, and local emergency management officials relay reports from public works crews already out on the roads.
National Weather Service forecasts drive the timeline. A Wind Chill Warning, a Winter Storm Warning, or an Excessive Heat Warning is strong evidence favoring closure or at least a delay. Forecasts aren’t always right, though, and the superintendent has to weigh the cost of being wrong in both directions. Cancel school and the sun comes out by 9:00 a.m.? Parents are annoyed but safe. Keep school open and conditions deteriorate mid-morning? Now buses are heading out into a storm to bring kids home, which is far more dangerous than keeping them home in the first place. Most superintendents err on the side of closing.
Many districts also use a two-hour delay as a middle option. The delay buys time for road crews to treat surfaces, for temperatures to climb above the worst wind chill readings, and for fog to burn off. If conditions improve by mid-morning, the school day proceeds on a shortened schedule.
Closed, or Just Remote?
The traditional snow day where kids stay home and do nothing academic is disappearing. As of the 2025–26 school year, roughly 23 states allow districts to use remote learning days during weather closures at their discretion or have no policy restricting the practice. Another 23 states cap how many remote days can count toward instructional time requirements, typically between three and five per year, with some allowing up to 10. Only four states plus the District of Columbia prohibit counting remote learning toward instructional time at all, meaning those districts have to schedule a makeup day for every weather closure.
When your district announces a closure, check whether it’s a full cancellation or a remote learning day. If it’s remote, your child will be expected to log in, complete assignments, and possibly attend live video sessions. Students with IEPs or 504 plans should still receive their accommodations during remote days.
Districts that need makeup days usually build two to five of them into the calendar from the start, often on holidays, teacher workdays, or at the end of the school year. If the days aren’t needed, students get them off. A handful of states let districts absorb the first few closure days without making them up, and when closures exceed all available options, districts can sometimes apply for a state waiver.
How You’ll Find Out
Districts push closure announcements out fast, usually between 5:00 and 6:00 a.m. The most reliable source is your district’s own notification system. Most use automated calls, text messages, and emails to reach parents who have registered their contact information. If you haven’t opted into your district’s alert system, do it before the first storm, not during it.
Beyond district alerts, school websites and official social media carry announcements. Local television and radio stations maintain running closure lists during weather events, and many have apps with push notifications. Some districts also post to parent communication platforms like ClassDojo or Remind.
Under Title II of the Americans with Disabilities Act, school districts must make sure emergency communications reach people who are deaf or hard of hearing, blind, or have low vision. That means auto-dialed TTY messages, text-based alerts, and captioned or sign-language-interpreted video should be part of any district’s notification plan.5ADA Best Practices Tool Kit for State and Local Governments. Chapter 7 Emergency Management
Outdoor Activities Run on Different Numbers
School closures and athletic cancellations follow different thresholds. Even on days when school stays open, outdoor practices, games, and recess can be called off when conditions make prolonged outdoor exertion dangerous.
For cold weather, the National Federation of State High School Associations recommends increased monitoring of athletes when wind chill drops below -18°F, the point where exposed skin freezes in 30 minutes or less. Below that threshold, the organization advises schools to consider postponing or shortening outdoor events.6NFHS. Guidelines for Competition in the Cold Frostbite risk stays below five percent when the ambient temperature is above 5°F, assuming athletes are dressed appropriately.
For heat, many districts and state athletic associations now use Wet Bulb Globe Temperature instead of air temperature or heat index. WBGT factors in temperature, humidity, wind, and sun angle to produce a single number closer to what the body actually experiences. When WBGT readings exceed about 92°F, conditions are considered too extreme for outdoor practice.7NFHS. Wet Bulb Globe Temperature (WBGT) – Why Should Your School Be Using It Some states have also adopted tiered systems based on the National Weather Service HeatRisk forecast, canceling all outdoor and unconditioned indoor activities when the forecast hits “Extreme” levels.
If your child plays outdoor sports, ask whether the school or athletic association has a written heat and cold policy. The NFHS recommends every school adopt one so the decision doesn’t come down to a coach’s judgment on game day.