The Winter Alert Hierarchy
Winter alerts follow the same watch → warning pattern as severe weather, but there are more types because winter storms produce different hazards (snow, ice, wind, cold).
Winter Storm Watch
Significant winter weather is possible in the next 24–48 hours. Heavy snow, ice, or a combination. This is your heads-up to prepare — get groceries, charge devices, fill prescriptions, check your generator.
Winter Weather Advisory
Winter weather is expected but not severe enough for a warning. Typically 2–4 inches of snow, light ice accumulation, or patchy freezing rain. Roads will be slick. Travel will be difficult but not impossible.
Winter Storm Warning
Dangerous winter conditions are imminent or occurring. Heavy snow (typically 6+ inches in 12 hours), significant ice accumulation, or a dangerous combination of winter hazards. Travel will be very dangerous to impossible.
Specialized Winter Alerts
Beyond the standard watch/advisory/warning, the NWS issues specific alerts for particular winter hazards:
Ice Storm Warning
Significant ice accumulation expected — typically 0.25 inches or more of ice on surfaces. This is one of the most dangerous winter events. Power lines and trees come down. Roads become impassable. Power outages can last days or weeks. Ice storms are more dangerous than most snowstorms.
Blizzard Warning
Sustained winds or frequent gusts of 35+ mph with heavy or blowing snow, reducing visibility to less than 1/4 mile for 3+ hours. It's not about how much snow falls — it's about wind and visibility. A blizzard can occur with no new snowfall if wind blows existing snow.
Wind Chill Warning
Dangerously cold wind chill values expected — typically -25°F or colder (varies by region). Frostbite can occur in minutes on exposed skin. Life-threatening for anyone caught outside without protection.
Freezing Rain Advisory
Light ice accumulation expected from freezing rain or drizzle. Not enough for an ice storm warning, but roads and sidewalks will be slick. Black ice is the main hazard — it's nearly invisible on pavement.
What to Do Before a Winter Storm
Prepare for Power Loss
Charge phones and battery banks. Fill bathtubs with water (for flushing toilets). Have flashlights, blankets, and a way to heat your home that doesn't produce carbon monoxide indoors.
Stay Off the Roads
The #1 cause of death in winter storms is vehicle accidents. If a winter storm warning or ice storm warning is issued, don't drive unless absolutely necessary. If you must, tell someone your route and expected arrival time.
Insulate Pipes
When temperatures drop below 20°F, exposed water pipes can freeze and burst. Open cabinet doors under sinks, let faucets drip, and insulate pipes in unheated areas like crawl spaces and garages.
Fill Up
Gas up your car, fill prescriptions, and get groceries before the storm hits. Gas stations and stores may close or lose power. Keep your car's gas tank at least half full through winter.
Regional Differences
Winter storm criteria vary by location. What triggers a winter storm warning in the Southeast would barely qualify as an advisory in Minnesota:
- Northern states — Winter storm warning typically requires 7–9+ inches of snow in 12 hours. These areas have plows, salt, and infrastructure for heavy snow.
- Mid-Atlantic and Southeast — 4–6 inches can trigger a warning. Fewer plows, less salt, and drivers with less experience on snow and ice.
- Deep South — Any measurable ice or 1–2 inches of snow can shut down a city. These areas have almost no snow removal infrastructure.
Your local NWS office sets the thresholds based on what's dangerous for your area, not a national standard.
Frequently Asked Questions
Why is ice more dangerous than snow?
Ice adds direct weight to power lines and tree limbs that snow (which is lighter and can be shaken off) doesn't create in the same way, and ice-coated roads are far more dangerous to drive on than snow-covered ones, which at least offer some traction.
What counts as a blizzard if there's no new snow falling?
A "ground blizzard" — strong wind lifting and blowing already-fallen snow, creating the same near-zero visibility as a blizzard with active snowfall. The NWS criteria (35+ mph wind, under 1/4 mile visibility, 3+ hours) doesn't require new snow to fall.
How is wind chill actually calculated?
It's based on a formula combining air temperature and wind speed to estimate the rate of heat loss from exposed skin — it doesn't affect inanimate objects like car radiators, only living tissue, which is a common misconception.
Can a Winter Storm Warning and a Wind Chill Warning be active at the same time?
Yes — they cover different hazards (snow/ice accumulation vs. dangerous cold), so a storm system can trigger both simultaneously if it brings heavy snow followed by an arctic cold snap.
Get Winter Storm Alerts on Your Phone
StormCast delivers every winter weather alert for your location — winter storm watches, warnings, ice storm warnings, blizzard warnings, wind chill advisories, and more. Alerts arrive within seconds of being issued.
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A note on this guide: This is general safety information, not medical or professional emergency advice, and specific criteria can vary by region. In an actual emergency, call 911 and follow instructions from local officials and the National Weather Service.