How Cold Is Too Cold for School? Wind Chill Rules Districts Use

There is no national cutoff, but the districts we found that publish one land between −18°F and −35°F, and most of them mean wind chill. Saint Paul calls off in-person school when the wind chill forecast for 6 AM is −35°F or colder, Urbandale, Iowa, cancels at an air temperature of −25°F or a wind chill of −30°F, and Buffalo will consider closing at a −18°F wind chill.

Others print no number and act on the National Weather Service instead. Anoka-Hennepin in Minnesota and Appleton in Wisconsin key on an Extreme Cold Warning, the alert that replaced the Wind Chill Warning in 2024. Chicago closed on January 23, 2026, when a Weather Service warning said wind chills could reach −35°F.

Cold can close school even when no snow falls at all. The line is far milder in the South, where the Weather Service issues an Extreme Cold Warning for metro Atlanta at 0°F. By our rule of thumb, the cold point at bus time is about −9°F in Atlanta, −23°F in Chicago and −34°F in Minneapolis.

At what temperature do schools close for cold?

On the district pages we found, the numbers fall between −18°F and −35°F, usually as a wind chill. These are the rules, each from the district’s own page:

• Saint Paul, Minnesota: a wind chill forecast of −35°F or colder at 6 AM, or snow that makes travel too hard. The day becomes a day off or an e-learning day.
• Urbandale, Iowa: cancels when the temperature is −25°F or the wind chill −30°F, going by the Weather Service.
• Kenosha, Wisconsin: its closing policy lists a sustained wind chill of −30°F or lower, or a sustained temperature of −20°F or lower, among its reasons.
• Madison, Wisconsin: “We will consider closing schools at negative 25 degrees,” its weather page says. It does not say whether that means the air or the wind chill.
• Buffalo, New York: will still consider closing at a wind chill of −18°F, and an Extreme Cold Watch or Warning sets off a fuller review.
• Anoka-Hennepin, Minnesota: likely to close when the Weather Service issues an Extreme Cold Warning, which the district describes as cold that can frostbite exposed skin in 10 minutes. An advisory alone is not enough.
• Appleton, Wisconsin: decides whether to close when an Extreme Cold Warning lasts through the hour before school starts.
• Chicago: prints no number, but its weather guidelines list air temperature and wind chill among its reasons to close.

A few more print no number at all. Milwaukee watches the Weather Service’s cold alerts, Minneapolis gives a number for indoor recess but none for closing, and Fargo weighs temperature and wind chill along with wind, roads and bus safety, saying its first choice is always to stay open.

Why do districts measure cold differently?

Because each one asks a slightly different question: the forecast or what is happening now, the air or the wind chill, and at which hour. Put the same morning through each rule and you can get different answers.

Saint Paul goes by the forecast for 6 AM. Kenosha’s rule says sustained, so a short dip may not count, and it also asks whether a warning is still in effect at 5 AM, because advance warnings are often canceled when storms change. Appleton asks whether a warning lasts through the hour before school. Urbandale and Kenosha set separate lines for air temperature and wind chill, while Madison names one number without saying which it means.

The hours all point at the same moment: the trip to school, when children wait at bus stops or walk. Our calculator reads the lowest wind chill in the forecast from 5 to 9 AM and compares it with the place’s cold point. By our rule of thumb, that cold point is the place’s normal December–February low minus 45°F, kept between −60°F and 0°F.

What is wind chill, and how is it worked out?

Wind chill is how cold the air feels on exposed skin once the wind is counted, worked out by the National Weather Service from just two numbers: the air temperature and the wind speed. Its wind chill chart prints the formula: 35.74 + 0.6215T − 35.75(V^0.16) + 0.4275T(V^0.16), with T the air temperature in °F and V the wind speed in mph.

The formula is defined only at 50°F or colder, with wind above 3 mph. The Weather Service’s own example: 0°F with a 15 mph wind gives a wind chill of −19°F, cold enough for exposed skin to freeze in 30 minutes. Move the sliders to try your own morning:

The number has limits, and the Weather Service lists them. Bright sunshine can raise the wind chill by 10°F to 18°F. The tests behind the formula used adults, so it says to be even more cautious with children. And frostbite needs freezing air: you can get it only when the real air temperature, not just the wind chill, is below freezing.

NOAA’s JetStream guide adds a warning about the number itself. A −40°F day with a 5 mph wind and a −20°F day with a 45 mph wind both work out to about −58°F, yet frostbite can set in within 10 minutes in the first and within 5 minutes in the second. In its words, “you cannot rely on the wind chill value alone.”

How fast can frostbite set in at the bus stop?

In minutes, at the cold that closes schools. The Weather Service’s wind chill brochure shades three frostbite bands on its chart: 30 minutes, 10 minutes and 5 minutes.

Districts use the same numbers. Chicago Public Schools warned of frostbite on exposed skin in as little as 10 minutes, and Anoka-Hennepin ties its closings to the Extreme Cold Warning level, when exposed skin can be frostbitten in 10 minutes. That is why so many rules look at the hour when children are at the bus stop.

What is an Extreme Cold Warning?

It is the Weather Service’s alert for extremely dangerous cold or wind chills that are expected or already happening, and it replaced the Wind Chill Warning in October 2024. The change came in Service Change Notice 23-44, effective on or about October 1, 2024:

• Wind Chill Warning became Extreme Cold Warning.
• Wind Chill Watch became Extreme Cold Watch.
• Wind Chill Advisory became Cold Weather Advisory.

The reason, in the Weather Service’s announcement: cold “can be dangerous with or without wind.” Its Amarillo office adds that the alerts now go by the temperature or the wind chill, with no wind threshold.

On its cold alerts page, a warning means extremely dangerous cold is expected or occurring, a watch means it is possible but its timing or place is still uncertain, and an advisory means dangerous cold that should stay below warning level. Older pages, including some of the Weather Service’s own, still use the old names.

As with snow, the lines are local. The warning starts at −25°F in Rochester, New York, in the example on the wind chill chart page, and at −30°F in northeast Wisconsin, as Appleton quotes it. Around Atlanta it starts at 0°F, with an advisory from 1°F to 10°F. In our calculator, the warning adds to the chance of a closing, and the watch and advisory add less.

Why do Southern schools close at milder cold?

Because cold is measured against what is normal for each place. The Weather Service sets its cold alerts by local criteria: its Atlanta office issues an Extreme Cold Warning for metro Atlanta at 0°F, while northeast Wisconsin’s waits for −30°F.

Southern districts name the machines and buildings. Fulton County, Georgia, lists whether diesel buses can start in extreme cold, and Gwinnett County says extreme cold can cause trouble for its diesel buses. Atlanta Public Schools lists extreme cold among its reasons to close, and Dallas checks with gas and utility companies on the energy to heat its buildings. None of the Southern district pages we read prints a cold number.

Our rule of thumb follows the same logic. Because the cold point is the normal winter low minus 45°F, it comes out about −9°F in Atlanta, against −23°F in Chicago and −34°F in Minneapolis and Saint Paul. Our Georgia and Minnesota pages list their cities.

When do schools keep recess inside?

Long before they close. Indoor-recess lines sit far above closing lines, so a cold morning can mean recess indoors on a normal school day:

• Saint Paul: inside when the wind chill is expected below −10°F, against −35°F to close.
• Kenosha: inside at 10°F or below, or a wind chill of 0°F or below, against a sustained −30°F wind chill on its closing list.
• Urbandale: inside at 10°F or lower.
• Anoka-Hennepin: inside at 0°F or a wind chill of −10°F.
• Bismarck, North Dakota: as a rule, no outdoor recess below a −10°F wind chill.
• Green Bay: outside only when the temperature, wind chill included, is above zero.

School news

INDOORRECESSTODAY

Sports have their own line. The Minnesota State High School League tells teams to cancel or postpone all activity at −20°F or a −40°F wind chill.

The whole page, on one map:

Cold school closings

• District lines
  • Saint Paul −35°F at 6 AM
  • Urbandale −30°F wind chill
  • Kenosha −30°F sustained
  • Buffalo weighs −18°F
• How it is measured
  • Forecast or sustained
  • Air or wind chill
  • The hour before school
• Weather Service
  • Wind chill formula
  • Extreme Cold Warning
  • Cold Weather Advisory
• Frostbite
  • 30 minutes
  • 10 minutes
  • 5 minutes
• The South
  • Warning at 0°F near Atlanta
  • Diesel buses
  • Building heat
• Recess
  • Inside from about 10°F to 0°F
  • Far above closing lines

Questions people ask

How cold does it have to be to cancel school in Minnesota?

Saint Paul calls off in-person school at a 6 AM wind chill forecast of −35°F or colder, and Anoka-Hennepin is likely to close on an Extreme Cold Warning; Minneapolis prints no closing number. By our rule of thumb, the cold point for Minneapolis and Saint Paul is about −34°F. Our Minnesota page has the rest of the state.

How cold does it have to be to cancel school in Wisconsin?

Kenosha lists a sustained −30°F wind chill or −20°F temperature, Madison considers closing at −25°F, and Appleton acts on an Extreme Cold Warning, which in northeast Wisconsin starts at −30°F. By our rule of thumb, the cold point is about −27°F in Milwaukee and −31°F in Madison. See our Wisconsin page.

Can school be canceled for cold with no snow?

Yes. Cold alone is a reason to close on many district pages. On January 23, 2026, Chicago closed on a Weather Service warning of wind chills as low as −35°F, and Anoka-Hennepin closed all its schools because an Extreme Cold Warning had been issued.

Do schools have two-hour delays for cold?

It depends on the district. Saint Paul says delayed starts are not logistically possible, and Anoka-Hennepin says it has no late-start option, so on a bitter morning the choice there is open or closed.

Can I keep my child home if school is open on a very cold day?

Several districts allow it. Anoka-Hennepin excuses the absence when the Weather Service has an extreme cold warning, watch or advisory out and the parent calls before school, Green Bay excuses it when a parent calls, and Fargo says parents may keep children home.

Sources: National Weather Service, Wind Chill Chart; National Weather Service, Cold Weather Warnings, Watches and Advisories; National Weather Service, Service Change Notice 23-44.

Facts checked October 29, 2026.

Updated October 29, 2026