Even a very small amount of freezing rain is considered dangerous , because it creates a nearly invisible layer of ice that can make walking and driving extremely slippery. Once ice starts to accumulate to around 0.25 inch (about 6 mm) or more, risks to trees, power lines, and infrastructure increase sharply.

Key danger levels

  • Any glazing (a “thin sheen” of ice)
    • Sidewalks, steps, and roads can become slick enough to cause falls and car crashes.
    • This level may look like just “wet pavement,” but traction is greatly reduced.
  • Around 0.10–0.25 inch of ice (light glaze)
    • Travel becomes very hazardous; vehicles can easily slide, especially on bridges and untreated roads.
* Power outages are still uncommon, but minor tree limb breakage can begin.
  • 0.25–0.50 inch of ice (disruptive ice storm)
    • Often called a “disruptive” ice storm: trees and power lines start taking damage.
* Numerous accidents and scattered to widespread power outages are likely.
  • More than 0.50 inch of ice (crippling ice storm)
    • Considered “crippling”: severe tree damage, many power lines down, power outages that can last for days.
* At around 1 inch or more, damage and outages can become widespread and long-lasting.

Why freezing rain is so risky

  • The rain falls as liquid but freezes on contact with surfaces below freezing, forming clear “glaze ice.”
  • This ice is hard to see, especially at night, so people often underestimate how slick it is.
  • It coats everything—roads, sidewalks, trees, power lines, cars—so danger comes from both slipping and falling objects like tree branches.

Practical safety tips

  • If freezing rain is in the forecast, avoid driving and walking outside unless absolutely necessary.
  • Watch for especially dangerous spots: bridges, overpasses, untreated side streets, and sloped driveways.
  • Prepare for power outages once forecasters start talking about 0.25 inch or more of ice accumulation.

Bottom line: any amount of freezing rain can be dangerous for travel, and once ice accumulations reach about 0.25 inch, the situation becomes serious for both safety and infrastructure.

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