# What an Ice Storm Warning means: how much ice, and freezing rain vs. sleet Published November 11, 2026, 12:46 PM ET By Ryan Hall, Y'all Written by our automated news desk from National Weather Service data. An Ice Storm Warning means damaging ice is expected from freezing rain, usually around 1/4 inch or more. The exact warning threshold is set locally, and about 1/4 inch makes travel dangerous or impossible and is likely to lead to snapped power lines and falling tree branches. Freezing rain coats surfaces in ice, while sleet falls as ice pellets, and this explainer covers both and what to do. ## Key points - **Freezing rain** is rain that freezes when it hits the ground, leaving a coat of ice on roads, walkways, trees and power lines. - **Sleet** is rain that turns to ice pellets before it reaches the ground. It can still make wet roads freeze and turn slick. - **Winter Weather Advisory:** the alert for smaller amounts of ice. - **Ice Storm Warning:** damaging ice is expected, typically more than 1/4 inch. The exact criteria are set locally. - **Winter Storm Warning:** can cover a storm that mixes ice with snow or sleet. An Ice Storm Warning means damaging ice is expected from freezing rain, usually around 1/4 inch of ice or more. At that amount, travel becomes dangerous or impossible, and snapped power lines and falling tree branches are likely. These points come from National Weather Service definitions and safety guidance. ## Freezing rain versus sleet Both start as rain, but they end differently. Freezing rain stays liquid until it reaches the ground or another surface, where it freezes and leaves a glaze of ice. That includes roads, steps, tree limbs and wires. Sleet freezes on the way down and arrives as small ice pellets. Sleet can make wet roads slick, but it is freezing rain that builds up on trees and power lines. That is why the Ice Storm Warning is tied to freezing rain. ## Winter Weather Advisory: smaller amounts of ice When ice is expected but the amount falls below the warning level, the National Weather Service uses a Winter Weather Advisory. Any ice on a road or walkway can make it slick. An advisory just says the ice is expected to be lighter than what a warning is built for. ## Ice Storm Warning An Ice Storm Warning is issued when ice accumulation is expected to meet or exceed the warning criteria for that area. The measurement is made on an elevated horizontal flat surface, not on the ground. The criteria are set locally and vary from state to state. Typically, a warning goes out when more than 1/4 inch of ice is expected. Treat that as a typical value, not a national rule. Your area's number may differ, but the alert means ice accumulation is expected to meet or exceed the locally defined warning criteria. ## How much ice it takes About 1/4 inch of ice is the benchmark. The National Weather Service says that much ice makes travel dangerous or impossible and likely leads to snapped power lines and falling tree branches. It strongly discourages travel at that level. Significant ice accumulations are usually 1/4 inch or greater. A quarter inch does not sound like much. But it can coat roads, walkways, trees and power lines in ice. ## Why ice brings down trees and power lines Freezing rain freezes on contact, coating branches and wires. Additional freezing rain can add to that ice accumulation. The weight can snap branches and power lines and pull down trees and utility lines. That can cause loss of power and communication while making walking and driving extremely dangerous. ## Winter Storm Warning: when ice mixes with snow Some storms bring ice along with snow or sleet. The National Weather Service can cover those with a Winter Storm Warning instead of an Ice Storm Warning. If your alert says Winter Storm Warning, read its text. The ice may be only part of the story. ## What to do - **Avoid travel.** Travel is strongly discouraged when ice reaches about 1/4 inch. You can check our [interstate driving outlook](/interstates) before you decide. - **Treat walking as risky too.** Ice on steps, driveways and sidewalks makes a short walk hazardous. - **Plan for the power to go out.** Snapped lines and falling branches can cut power and communication, so get ready before the ice arrives. - **Keep an eye on falling limbs.** Trees and branches are among the hazards in an ice storm. - **Check what is active for you.** See every alert in effect on our [warnings page](/warnings), and get free [Y'all Alerts](/alerts) sent to you. For the latest on where ice is expected, see our [winter storm outlook](/winter). More on: [Weather explainers](https://ryanhallyall.com/news/topic/weather-explainers) ## Sources - [NWS Instruction 10-513, "WFO Winter Weather Products Specification" (November 6, 2024), Table 1 and Appendix D](https://www.weather.gov/media/directives/010_pdfs/pd01005013curr.pdf), NOAA National Weather Service, issued November 5, 2024, 7:00 PM ET - [NWS safety page "Winter Weather Warnings, Watches and Advisories"](https://www.weather.gov/safety/winter-ww), NOAA National Weather Service - [NWS Glossary, "ice storm"](https://forecast.weather.gov/glossary.php?word=ice%20storm), NOAA National Weather Service --- Canonical: https://ryanhallyall.com/news/what-an-ice-storm-warning-means From Ryan Hall, Y'all (https://ryanhallyall.com). Always follow official warnings from the National Weather Service.