Most schools do not use a single universal temperature for closing; instead, they look at wind chill and safety risks, and many districts start seriously considering closure when wind chill drops somewhere around −20∘-20^\circ −20∘F to −35∘-35^\circ −35∘F. There are big local differences though, so the exact number depends on your district’s written policy (if it has one) and how long students are exposed to the cold traveling to and from school.

No single magic number

There is no nationwide rule like “school always closes at X degrees.”

  • Each district or region sets its own guidelines or just makes case‑by‑case decisions.
  • Superintendents consider many factors: bus safety, walking distance, building heating, and whether many students lack proper winter clothing.

In online discussions about specific cities, parents and teachers often note that closures happen during “polar vortex” type events, not just on a typical cold winter day.

Typical temperature / wind chill ranges

Many recent examples and guidelines cluster around these approximate thresholds (all Fahrenheit):

  • Wind chill between about −20∘-20^\circ −20∘F and −35∘-35^\circ −35∘F is a common range where districts start canceling or delaying school because frostbite can occur on exposed skin in 10–30 minutes.
  • Some Michigan and Wisconsin districts, for example, talk about:
    • Closing or delaying when wind chill reaches around −30∘-30^\circ −30∘F to −35∘-35^\circ −35∘F.
* Using an actual‑temperature benchmark like −15∘-15^\circ −15∘F if there is little or no wind.

Because wind makes such a big difference, a day at 5∘5^\circ 5∘F with strong wind can be treated as more dangerous than a calm day at −10∘-10^\circ −10∘F.

What schools actually look at

When deciding whether to close, administrators usually weigh a mix of:

  1. Wind chill and frostbite risk
    • Wind chill is often the main metric, because it captures how fast body heat is lost.
 * Many guidelines are explicitly tied to wind chills where exposed skin could get frostbite in 30 minutes or less.
  1. Time and length of travel
    • How long students wait at bus stops or walk to school matters a lot.
 * Long rural bus routes or large walking zones can push officials to close at “warmer” values than a compact urban district might.
  1. Building and transport safety
    • Concerns include buses starting reliably, roads and sidewalks being safe, and whether schools can keep classrooms warm enough.
  1. Local norms and past practice
    • Some big districts rarely close and only do so in repeated subzero days or severe polar vortex events.
 * Others have more formal written wind chill charts that parents can look up.

How to find your district’s cutoff

If you want a concrete answer for your area:

  1. Check your district website for “winter weather” or “cold weather closing guidelines”; many now publish charts like “close if wind chill ≤ −30∘-30^\circ −30∘F.”
  1. Look at recent closure announcements and note the wind chill they referenced; that gives you a practical rule‑of‑thumb range.
  1. Ask your school office or principal if they follow a specific wind chill threshold or decide case by case.

In practice, most students only see cold‑related closures on those brutal days when the wind chill drops below about −20∘-20^\circ −20∘F, often paired with headlines about “dangerous cold” or “polar vortex” in the local news.

TL;DR: For many districts today, it usually has to feel at least around −20∘-20^\circ −20∘F to −35∘-35^\circ −35∘F with wind chill for cold alone to close schools, but the exact number depends on local policy and safety conditions, not a universal rule.

— Information gathered from public forums or data available on the internet and portrayed here.