How Wind Chill Alone Can Close Schools, Even With No Snow
Some of the coldest closures happen under clear skies with zero snowfall. The National Weather Service and Environment Canada jointly developed the modern wind chill temperature index in the early 2000s, and the resulting chart shows how quickly frostbite risk rises as wind chill drops, not just how uncomfortable it feels.
At a wind chill of around negative nineteen degrees Fahrenheit, the NWS chart shows exposed skin can freeze in approximately thirty minutes. As wind chill drops further, that window shortens fast, into roughly ten minutes in the negative thirty-five to negative fifty-nine degree range, and around five minutes at negative sixty or colder.
Several Minnesota districts publish their own specific wind chill thresholds, which shows just how differently districts translate that same NWS chart into a real policy.
Anoka-Hennepin School District
Minnesota's largest district says it will likely close when the National Weather Service issues an extreme cold warning indicating frostbite is possible on exposed skin in less than ten minutes, according to the district's own published cold weather policy.
Duluth Public Schools
Sets its own line lower still, at a sustained wind chill of negative forty degrees, or negative forty-five at its coldest point, and the district says it consults directly with the local National Weather Service office and its bus contractor before making the call.
Minneapolis and St. Paul Public Schools
Both use a specific forecast checkpoint, closing when the wind chill forecast for six or six-thirty that morning reaches negative thirty-five degrees or colder.
These policies are not just theoretical. In January 2014, conditions were severe enough statewide that Minnesota's governor at the time ordered every public school in the state closed on a single day, with wind chill readings near negative forty-eight in the Twin Cities, according to the Minnesota Department of Natural Resources.
Frostbite Time by Wind Chill (Source: National Weather Service, jointly developed with Environment Canada)
Minneapolis and St. Paul Public Schools
Both use a specific forecast checkpoint, closing when the wind chill forecast for six or six-thirty that morning reaches negative thirty-five degrees or colder.
These policies are not just theoretical. In January 2014, conditions were severe enough statewide that Minnesota's governor at the time ordered every public school in the state closed on a single day, with wind chill readings near negative forty-eight in the Twin Cities, according to the Minnesota Department of Natural Resources.
Frostbite Time by Wind Chill (Source: National Weather Service, jointly developed with Environment Canada)
| Wind chill (°F) | Approximate Celsius | Approximate time to frostbite | Risk level |
|---|---|---|---|
| Around −19°F | −28°C | About 30 minutes | Increasing risk |
| −35°F to −59°F | −37°C to −51°C | About 10 minutes | High risk |
| −60°F or colder | −51°C or colder | About 5 minutes | Extreme risk |
Named District Wind Chill Thresholds
| District | State | Published threshold |
|---|---|---|
| Anoka-Hennepin School District | Minnesota | NWS extreme cold warning, frostbite possible in under 10 minutes |
| Duluth Public Schools | Minnesota | Sustained wind chill of −40°F, or −45°F at coldest |
| Minneapolis Public Schools | Minnesota | 6:30 a.m. forecast wind chill of −35°F or colder |
| St. Paul Public Schools | Minnesota | 6 a.m. forecast wind chill of −35°F or colder |
Can schools close with no snow at all?
Yes. Minnesota districts publish policies allowing closures based on extreme wind chill alone, particularly when frostbite risk becomes dangerous for students waiting at bus stops. This page currently documents Minnesota examples specifically; similar policies may exist elsewhere but are not yet confirmed here.
What wind chill typically closes schools in Minnesota?
It varies by district. Anoka-Hennepin closes based on an NWS extreme cold warning (frostbite in under 10 minutes), while Duluth uses a specific sustained wind chill of −40°F.
How fast can frostbite actually happen?
At a wind chill of about −19°F (−28°C), the NWS chart shows frostbite in approximately 30 minutes. That window drops to about 10 minutes between −35°F and −59°F, and to about 5 minutes at −60°F or colder.
●National Weather Service, wind chill temperature index chart (developed jointly with Environment Canada)
●Anoka-Hennepin School District, published cold weather policy
●Duluth Public Schools, published cold weather policy
●Minneapolis Public Schools and St. Paul Public Schools, published cold weather policies
●Minnesota Department of Natural Resources, January 2014 statewide closure record
Related reading: See why freezing rain often closes more schools than heavy snow, and how much snow it actually takes to close schools region by region. Back to the SnowDay Score predictor.
Related reading
Extreme cold closures show up most often in the coldest regions we cover. See the Duluth, MN predictor and the Marquette & the Upper Peninsula, MI predictor, both of which regularly see closures driven by cold alone. For the full picture of how our estimates are built, see the methodology page, or head back to the SnowDay Score predictor to check your own city.