Iowa Snow Day Calculator: Chances, Cold Rules and Make-Up Time

Iowa’s six largest cities get nearly the same snow, 28 to 36 inches a year, so by our rule of thumb their schools all close about half the time somewhere between 5 and 6 inches overnight. What separates them is cold: our cold points, the morning wind chills at which schools start closing for cold by our rule, run from −28°F in Davenport to −32°F in Sioux City.

Iowa districts put cold in writing too. Urbandale generally cancels school at an air temperature of −25°F or a wind chill of −30°F, going by the Weather Service, and Des Moines weighs temperature and wind chill alongside snow and roads. The calculator reads the National Weather Service forecast for the part of your ZIP code where most people live, hour by hour, including the wind chill from 5 to 9 AM.

How a closing is paid back depends on a choice each district makes. Under Iowa Code section 279.10, a school must hold 180 days or 1,080 hours of instruction, whichever it picks. Lost time is made up by extending the year, and up to five days or 30 hours a year can be taught online.

How much snow closes school in Iowa?

By our rule of thumb, about 5 inches overnight in Iowa City, 5.5 in Cedar Rapids and Ankeny, and 6 in Des Moines, Davenport and Sioux City. Each is the snowfall at which schools there close about half the time, worked out from the city’s normal yearly snowfall.

Iowa's six largest cities: normal snowfall a year (NOAA 1991–2020) and the snowfall and wind chill at which, by our rule of thumb, schools there usually close.

Our rule of thumb: the usual closing point is 0.5 × (normal snowfall a year)^0.7, the cold point the normal December–February low minus 45°F. How the calculator works.

Iowa City is the least snowy of the six at 27.8 inches a year and Sioux City the snowiest at 35.6, a gap of only an inch in the closing point. If your district rarely closes, or closes easily, tell the calculator and it moves the point.

Wind changes the count. Gusts of 25 mph or more while an inch or more falls make each inch count more in the calculator, and snow that falls with the air above freezing counts less, since it melts on the roads. A Weather Service warning raises the chance more than a watch or an advisory does.

Timing matters as much as amount. A 2018 letter from the Des Moines superintendent explained that the district looks at whether there is time to clear the roads after the snow stops. The calculator does the same in its own way: snow overnight and during the bus run counts in full, snow the morning before only about a third.

Where does Iowa get the most snow?

Mostly in the north. NOAA has snowfall normals for 141 Iowa stations, with a middle value of 31.1 inches a year, and the snowiest are St. Ansgar (47.7 inches), Ocheyedan and Little Sioux (45.6 each), Mason City’s airport (44.4) and Spencer (43.3). Dubuque’s airport, in the east, averages 42.5.

Normal snowfall a year and normal December to February low at each of the 141 weather stations in Iowa with a snowfall normal in NOAA's U.S. Climate Normals for 1991–2020, with each station's location, elevation and how complete its record is.

The 10 snowiest and 5 least snowy of 141 stations in Iowa

Download “Normal snowfall at Iowa weather stations, 1991–2020” (CSV, opens in Excel)

Built from: U.S. Climate Normals, 1991–2020 (National Centers for Environmental Information).

The least snowy are in the south: Blockton averages 18.0 inches, Fort Madison 18.1, Hastings 19.6 and Mount Ayr 20.5. Even Iowa’s snowiest station gets less than 48 inches a year, so by our rule of thumb no part of the state has a closing point much above 7.5 inches.

Do snow days have to be made up in Iowa?

Yes, by extending the school year, unless the calendar had time to spare. Section 279.10 requires “not less than one hundred eighty days or one thousand eighty hours of instruction,” and we found no set number of free snow days; the law speaks of schools that extend the calendar after bad-weather closings. The school calendar may start no sooner than August 23.

Which calendar a district chose changes what a short day is worth. In a 180-day district each day needs at least 6 hours, but the Department of Education’s guidance, dated April 15, 2026, lets such a school record a late start or early dismissal forced by health or safety as a minimum school day, so it still counts. An hours-based district has no minimum day length, but it may not count the time it missed. A two-hour delay costs one kind of district nothing and the other two hours.

Seniors get a break. The law lets a board excuse a graduating senior who has met the requirements from the days added for bad weather, and the department’s guidance lets a board excuse graduating seniors from up to 30 hours or 5 days by board policy. We found no state waiver for snow days.

Can Iowa schools switch to online learning instead?

Yes, for a limited amount. Section 279.10 allows no more than five days or 30 hours of instruction a year to be delivered mainly over the internet, and the department’s guidance counts them toward the 180 days or 1,080 hours.

The limit is not about weather: it covers online teaching for any reason. We found no Iowa rule that sets up weather e-learning days of their own, with an approval step or a notice period, so ask your district whether it saves its online days for storms.

How cold does it have to be to close school in Iowa?

In Urbandale, −25°F air or a −30°F wind chill: the district’s weather page says it generally cancels school at those readings, going by the Weather Service. Des Moines watches temperature and wind chill but gave no number in the letter we read, and the state rules we read set none.

By our rule of thumb, schools start closing for cold at a morning wind chill of about −28°F in Davenport, −29°F in Des Moines, Ankeny and Iowa City, −30°F in Cedar Rapids and −32°F in Sioux City: 45 degrees below each city’s normal December-to-February low. Urbandale’s −30°F wind chill sits right alongside them. The calculator raises its chance when the Weather Service has an Extreme Cold Warning in force, the alert that replaced the Wind Chill Warning in October 2024.

Who decides, and when do Iowa families hear?

The local district decides, and the districts we read all announce by 6 a.m. Des Moines Public Schools lists four choices: cancel classes with offices open, cancel with offices closed, dismiss two hours early or start two hours late. The superintendent’s 2018 letter set an announcement no later than 6:00 AM and added, “If no announcement is made, then it is a school day.”

Urbandale aims to tell families by 5:45 a.m. for morning trouble and by 11:00 a.m. for afternoon trouble, and prefers one decision in the morning to a night-before call it might have to change. In Cedar Rapids, the superintendent decides with the transportation manager, nearby superintendents, the Weather Service and local meteorologists, and a late start or cancellation is usually announced by 5:30 a.m.

Wherever you are, check your district’s website, app or local TV and radio. The calculator gives odds; the district makes the call.

Is it a snow day in Iowa tomorrow?

Your district decides, usually before 6 a.m.; the calculator gives the odds from tomorrow’s forecast, and this map sums up what moves them.

Snow days in Iowa

• Snow that closes schools
  • Iowa City 5 in
  • Cedar Rapids 5.5 in
  • Des Moines 6 in
• Cold
  • Urbandale −25°F air or −30°F wind chill
  • our points −28°F to −32°F
• The school year
  • 180 days or 1,080 hours
  • made up by extending
  • seniors can be excused
• Online days
  • Up to 5 days or 30 hours
  • for any reason
• Morning calls
  • Cedar Rapids 5:30
  • Urbandale 5:45
  • Des Moines 6:00

Questions people ask

Do Iowa schools have to make up snow days?

Yes, if a closing leaves them short of 180 days or 1,080 hours. They make up the time by extending the school year, though graduating seniors can be excused.

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

There is no state number. Urbandale generally cancels at −25°F or a −30°F wind chill, and by our rule of thumb Iowa schools start closing for cold at a morning wind chill of about −28°F to −32°F.

Does a two-hour delay count in Iowa?

It depends on the district’s calendar. A 180-day district may count a late start forced by health or safety as a minimum school day; an hours-based district cannot count the time it missed.

What time do Des Moines schools announce a closing?

The superintendent’s 2018 letter promised an announcement no later than 6:00 AM, and said that no announcement means school is on.

Sources: Iowa Code section 279.10; Iowa Department of Education, instructional time guidance (April 2026); Urbandale Community School District, weather.

Facts checked October 29, 2026.

Updated October 29, 2026