There is no single temperature where all schools cancel; it depends on the local district’s policy, wind chill, and how long students are outside. Most districts that publish “numbers” are looking at very cold, dangerous wind chills rather than just the air temperature.

Typical cold-weather thresholds

• Many U.S. districts start considering delays or closures when wind chill is around -20 °F or lower, because frostbite risk increases for kids waiting at bus stops.

• Some districts use colder thresholds, such as sustained wind chill near -30 °F or actual temperatures near -15 °F during travel times.

• A few policies or recommendations say schools should close if wind chill is around -35 °F or colder due to very high frostbite risk.

• In some Canadian districts, policies mention partial or full closure around -35 °C with wind chill near -45 °C or colder.

Why there is no universal number

• There is no state‑ or country‑wide law in many places that says “you must close at this exact temperature”; each district sets its own guidelines.

• Decisions usually consider: wind chill, road conditions, how long students wait outside, availability of heated buses, and whether buildings are warm and functioning. Districts may also choose a two‑hour delay instead of a full closure if temperatures are expected to improve after sunrise.

What you can do

• Check your specific school district’s website or handbook for its “inclement weather” or “extreme cold” policy; most post their exact thresholds and when they announce closures.

• If a day is extremely cold but school is still open, families can usually choose to keep students home if they believe conditions are unsafe, following the normal absence reporting rules.