Ice vs. Snow: Why Freezing Rain Can Close Schools Faster
A thin coating of ice can be harder for road crews to manage safely than several inches of dry snow, and three real, documented events show why.
Portland, Oregon, January 2024
Portland Public Schools, Oregon's largest district, closed for two consecutive days in mid-January 2024 as an ice storm coated the region, part of a longer stretch of storm-related closures that week, according to Oregon Public Broadcasting . The National Weather Service measured between a quarter and a half inch of ice at its Portland office, according to weather.com , and the NWS Ice Storm Warning itself specified “ice accumulations of one quarter to one half inch” for the greater Portland metro area, according to a local radio station's report quoting the warning text directly . Portland's Bureau of Transportation uses road salt on selected priority snow-and-ice routes, a policy adopted after the severe winter storms of 2016 and 2017, according to the city's own winter weather policy page . Before that shift, the city largely avoided salt for environmental reasons. The Oregon Department of Transportation also salts state highways, a shift confirmed by KGW news reporting on the change. Even with that equipment in place, a thin ice layer on secondary roads and sidewalks was still enough to keep the district closed.
Texas, February 2021
During Winter Storm Uri, the National Weather Service recorded up to half an inch of ice accumulation across North and Central Texas, alongside snow that reached 5 inches at Dallas-Fort Worth International Airport, according to NOAA's National Centers for Environmental Information . Schools across Texas experienced widespread closures for days, driven largely by the ice and the state's road infrastructure not being built for sustained freezing conditions.
Memphis, Tennessee, and Dallas/Austin, Texas, January 2023
Memphis-Shelby County Schools, serving about 100,000 students, canceled classes due to freezing rain and hazardous road conditions, and school systems in Dallas and Austin also canceled classes the same week, according to CBS News reporting on the storm.
In each of these three documented cases, the deciding factor was ice on roads and sidewalks, not total snowfall. This is not a claim that ice closes more schools nationally overall, only that these specific, sourced events show ice triggering closures at low accumulations.
Ice vs. Dry Snow, Real Comparison
| Factor | Dry snow | Ice / freezing rain |
|---|---|---|
| Road treatment difficulty | Snow can usually be plowed and treated, though packed snow may still require salt or abrasives | Ice bonds to pavement, harder to remove |
| Visibility impact | Reduces visibility during the storm | Can be nearly invisible (“black ice”) after |
| Real example | N/A, direct comparison | Portland, Jan 2024: two-day closure contributed to by a quarter to half inch of ice (NWS measurement) |
| What the documented examples show | Lower closure likelihood at low accumulation, unless paired with wind or timing | Higher closure likelihood even at a fraction of an inch, in the specific sourced cases above |
Why can ice close schools at lower accumulations than snow?
Ice can bond to roads, remain difficult to see, and require more time to treat than dry snow. In the documented Portland example, the National Weather Service measured a quarter to half inch of ice, which contributed to two consecutive closure days.
Does Portland use road salt on icy roads?
Yes. Portland's Bureau of Transportation uses salt on selected priority snow-and-ice routes, a policy in place since the severe storms of 2016 and 2017. The Oregon Department of Transportation salts state highways as well.
Can a small amount of ice really close an entire school district?
In the documented Portland example, yes: an ice storm measured by the National Weather Service at a quarter to half inch of accumulation contributed to Oregon's largest school district closing for two consecutive days in January 2024.
●Oregon Public Broadcasting (OPB), “Portland, Beaverton among districts to cancel classes,” January 2024
●Weather.com, “Oregon Ice Storm Leaves At Least Three Dead,” January 2024
●KXL, “Ice Storm Impact,” quoting the National Weather Service Ice Storm Warning text directly
●City of Portland, Bureau of Transportation, “Winter Weather Basics and FAQ”
●KGW, “Yes, Portland uses road salt when it snows”
●NOAA National Centers for Environmental Information, “The Great Texas Freeze: February 11-20, 2021”
●CBS News, winter storm school closure reporting, January 2023
Related reading: How much snow actually closes schools, region by region, how wind chill triggers closures with no snowfall, and the Fairfax County, VA predictor.
Related reading
Freezing rain risk varies sharply by region and by how closure decisions are made locally. See the Fairfax County, VA predictor, where a light glaze can be more disruptive than several inches of snow, or the Ontario predictor, where bus cancellations and school closures are decided separately. 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.