Winter Weather Guide 2026-27
What each kind of winter storm and winter alert means, when cold becomes dangerous, and how to get your home and car ready before the first storm of the season.
When Does Winter Start?
Meteorological Winter
Starts December 1, 2026, and runs through the end of February. Forecasters and climatologists use these three whole months because they make one winter's records easy to compare with another's.
Astronomical Winter
Begins at the December solstice, on December 21, 2026, at 3:50 p.m. Eastern (12:50 p.m. Pacific), and lasts until the March equinox. The solstice is the shortest day of the year in the Northern Hemisphere.
Winter storms follow neither calendar. Snow, ice, and hard freezes can arrive well before December and continue into spring.
Types of Winter Precipitation
What reaches the ground depends on the temperature of the air between the cloud and the surface. One storm can drop freezing rain on one side of town and sleet on the other, decided by a warm layer only a few hundred feet thick. A fifth type, graupel, is soft white pellets that form when supercooled droplets freeze onto snowflakes.
Snow
Ice crystals that form in clouds and fall without melting. Accumulates and can cause travel issues, but is generally the safest form of winter precipitation.
Sleet
Ice pellets that bounce when they hit. Snow melts in a warm layer, then refreezes before reaching the ground. Makes roads slippery.
Freezing Rain
Most dangerous. Falls as liquid rain but freezes on contact with cold surfaces. Creates ice glazes on roads, trees, and power lines.
Wintry Mix
Combination of precipitation types, often occurring when temperatures hover near freezing. Can change rapidly as temperatures fluctuate.
Types of Winter Storms
These six names come up in winter forecasts across the United States and Canada. Each has its own region, pace, and main hazard.
Nor'easter
A nor'easter is a storm along the East Coast, named for the northeast wind it drives onshore. Most frequent and strongest from September through April, it can bring heavy snow or rain, gale-force wind, rough seas, and coastal flooding to the corridor from Washington to Boston.
Alberta Clipper
An Alberta clipper is a fast-moving low that drops southeast out of Alberta across the Plains, Midwest, and Great Lakes. It usually brings light snow, strong wind, and a push of colder air behind it.
Lake-Effect Snow
Lake-effect snow forms when cold air crosses the open, warmer water of the Great Lakes and picks up heat and moisture. It falls in narrow bands that can produce 2 to 3 inches an hour or more while a nearby town stays sunny.
How lake-effect snow works →Ice Storm
An ice storm is freezing rain that builds a glaze of ice on roads, trees, and power lines. About a quarter inch is usually enough for an Ice Storm Warning, and heavier ice brings down tree limbs and power lines.
Blizzard
A blizzard is defined by wind and visibility, not by how much snow falls: wind of 35 mph or more and visibility below a quarter mile for at least three hours. Blowing snow alone can qualify, with no new snow falling.
Atmospheric River
An atmospheric river is a long, narrow corridor of water vapor that comes ashore on the West Coast. Lifted over the mountains, it produces prolonged heavy rain at lower elevations and heavy snow higher up, which builds the Sierra Nevada snowpack.
Atmospheric rivers explained →Two smaller hazards are worth knowing. Thundersnow is thunder and lightning during heavy snow, and freezing fog can leave a thin coat of ice on roads with no precipitation falling. For why totals from one storm differ so much from town to town, read why snow forecasts vary. For where the coldest arctic outbreaks come from, read what the polar vortex is.
Understanding Wind Chill
Wind chill describes how cold it feels on exposed skin when wind is factored in. Moving air accelerates heat loss, so the body cools as if the air were much colder than the thermometer shows.
Above 32°F
Wet conditions still pose risks
Stay dry and dress for the conditions and time outdoors
0°F to 32°F
Cold
Limit outdoor exposure, dress warmly
Below 0°F
Dangerous
Frostbite risk, minimize time outdoors
Wind chill alone cannot tell you whether outdoor exposure is safe. Rain, sweat, wet clothing, and time outside also matter. The CDC notes that hypothermia can occur even above 40°F when someone becomes chilled by rain, sweat, or cold water.
Winter Storm Alerts
The National Weather Service uses three levels for winter weather: a watch when a hazardous event is possible, a warning when it is expected or under way, and an advisory for conditions that are hazardous but below warning level. The snow, ice, and cold thresholds behind each alert are set by the local forecast office. Offices in places used to snow set them higher, and offices where a small amount causes serious problems set them lower.
Winter Storm Watch
Conditions are favorable for snow, sleet, ice, or lake-effect snow to reach local warning levels, but the timing, track, or amounts are still uncertain. Forecasters issue it once they are at least 50 percent confident. Stock supplies, review travel plans, and charge devices.
Winter Storm Warning
Heavy snow, sleet, ice, or a combination is occurring, imminent, or very likely (80 percent confidence or more) and is expected to reach local warning levels. Finish preparing and avoid travel if you can.
Winter Weather Advisory
Snow, blowing snow, or sleet is expected to reach local advisory levels but stay below a warning. It also covers freezing rain and lake-effect snow, which used to have advisories of their own. Expect slick roads and allow extra travel time.
Blizzard Warning
Sustained wind or frequent gusts of 35 mph or more, with falling or blowing snow frequently cutting visibility below a quarter mile for three hours or longer. Conditions are life-threatening. Do not travel.
Ice Storm Warning
Freezing rain is expected to leave ice at or above the local warning level, usually around a quarter inch or more. Expect dangerous roads, falling limbs, and power outages. Stay home if you can.
Snow Squall Warning
A snow squall is about to cut visibility to a quarter mile or less on freezing roads, or to bring a flash freeze as visibility drops. The warning covers a small area, like a tornado or severe thunderstorm warning, and lasts 30 to 60 minutes. Delay travel until it passes. If you are already driving, slow down, turn on your headlights and hazard lights, and leave extra room.
Lake Effect Snow Warning
Lake-effect snow is expected to reach local warning levels, usually in narrow bands that affect a limited area. Each NWS region decides whether to use this alert or to issue a Winter Storm Warning for heavy lake-effect snow instead, so near the Great Lakes either one can describe the same hazard.
Extreme Cold Watch and Warning
Dangerously low air temperatures or wind chills are possible (watch) or expected (warning). These replaced the Wind Chill Watch and Wind Chill Warning on October 1, 2024, so they cover cold that is dangerous with or without wind. Limit time outside and cover exposed skin.
Cold Weather Advisory
Air temperatures or wind chills are expected to reach the local advisory level but stay below an Extreme Cold Warning. It replaced the Wind Chill Advisory on October 1, 2024. Dress in layers and keep trips outside short.
Freeze Warning and Frost Advisory
These protect plants and crops and are issued only during the local growing season. A Freeze Warning means a low of 32°F or colder. A Frost Advisory means a low of 33°F to 36°F on a clear, calm night when frost can form. A Freeze Watch comes first when a freeze is possible in the next 12 to 48 hours. The Hard Freeze Warning was folded into the Freeze Warning in October 2024.
Winter 2026-27 and El Niño
El Niño is in place heading into this winter. It shifts the winter storm track south, which changes the odds for the season across North America. El Niño winters tend to be milder than average across the northern United States and western Canada, and wetter and stormier across California and the southern states. Drier conditions are more likely in the northern Rockies and the Ohio and Tennessee valleys, and snowfall tends to run below average around the Great Lakes, interior New England, and the Pacific Northwest.
These are tendencies across many winters. Any single storm or cold outbreak can still run against them.
How strong this El Niño is and what NOAA expects →Prepare Your Home for Storms and Power Outages
Before the Storm
- ✓Several days of food, water, and prescription medicine, plus supplies for infants and pets
- ✓Flashlights, spare batteries, and a battery-powered NOAA Weather Radio
- ✓Smoke alarms and carbon monoxide detectors with battery backup, tested and working
- ✓Heating fuel topped up early, since deliveries can be delayed for days after a storm
- ✓Insulation, caulk, and weatherstripping to keep cold air out, and a plan to keep pipes from freezing
- ✓Phones and backup batteries charged before the storm arrives
If the Power or Heat Goes Out
- ✓Run a generator outdoors only, at least 20 feet from windows, doors, and attached garages
- ✓Never heat your home with a gas stovetop or oven
- ✓Use a fireplace, wood stove, or space heater only with proper ventilation
- ✓Close off rooms you do not need and stuff towels or rags under the doors
- ✓Wear loose, warm layers, and take one off before you start to sweat
- ✓Keep eating and drinking water: food gives your body the energy to make heat
Carbon monoxide has no color or smell and can be fatal. Keep generators and grills outdoors and away from windows.
Winter Driving Safety
Before You Drive
- ✓Clear all snow and ice from windows, mirrors, and lights
- ✓Keep your gas tank at least half full
- ✓Check tire pressure and tread depth
- ✓Tell someone your route and expected arrival time
- ✓Keep an emergency kit in your car
While Driving
- ✓Reduce speed and increase following distance
- ✓Brake gently to avoid skidding
- ✓Watch for black ice, especially on bridges
- ✓Use low-beam headlights in snow
- ✓If you skid, steer in the direction you want to go
Winter Car Emergency Kit
- ✓Blankets or sleeping bags
- ✓Extra warm, dry clothing
- ✓Flashlight with extra batteries
- ✓Phone charger
- ✓First-aid kit
- ✓High-calorie, non-perishable food
- ✓Water
- ✓Sand or cat litter for traction
- ✓Shovel
- ✓Windshield scraper and brush
- ✓Booster cables
- ✓Tow rope
If you are stranded, stay with the vehicle. Run the engine for about 10 minutes each hour with a window cracked open, keep the exhaust pipe clear of snow, and tie a bright cloth to the antenna or door so rescuers can see you.
Signs of Frostbite and Hypothermia
Frostbite
Signs: redness or pain at first, then numbness and skin that looks white or grayish-yellow and feels unusually firm or waxy. It most often affects the face, fingers, and toes.
What to do: get medical care as soon as you can. Until then, get to a warm room and warm the area with warm water or body heat. Do not rub or massage it, and do not use a heating pad, fireplace, or other direct heat. Avoid walking on frostbitten feet or toes.
Hypothermia
Signs: shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech, and drowsiness. In babies, look for bright red, cold skin and very low energy.
What to do: a body temperature below 95°F is an emergency, so get medical help right away. While help is on the way, move the person somewhere warm, remove wet clothing, and warm the center of the body first (chest, neck, head, and groin) under dry blankets.
Source: CDC winter weather guidance.
Track Winter Storms with WeatherAI
Follow a winter storm from the first forecast to the official warning: snowfall in the daily forecast, alerts from the National Weather Service and Environment Canada, and a notification when the snow forecast reaches the amount you set.
Snowfall in the Forecast
See expected snowfall day by day, on Apple Watch too. Choose WeatherAI Forecast as your source for a daily snow probability, or the National Weather Service for the official U.S. forecast.
Official Winter Alerts
Winter alerts from the National Weather Service and Environment Canada, from Winter Storm Warnings to Extreme Cold Warnings, with the full official text. Get push notifications for your current location and up to 10 more places on the free plan.
Custom Snowfall Rules
Pick a snowfall amount and a time of day. WeatherAI checks the forecast at that time and notifies you when it reaches your number. Rules also work for temperature, feels-like temperature, and wind gusts, and they come with Standard and Pro.
Winter Guidance from the Forecasters
Read Weather Prediction Center winter-weather guidance and discussions for the national picture, and your local NWS office's Area Forecast Discussion for the reasoning behind the forecast where you live.
Winter Weather Tools
Keep Reading on Winter Weather
How outlooks, watches, and warnings fit together, how the forecast models differ, what falling pressure tells you, and tools for planning around the cold.
Guide
NWS Outlook vs Watch vs Warning
Know how alert wording changes from early awareness to immediate action.
Guide
GFS vs HRRR vs NAM
Learn which forecast model to trust for different situations and how to interpret model data.
Guide
Barometric Pressure Explained
What barometric pressure means, how it predicts weather changes, and how to read pressure trends.
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Professional Radar
Explore high-resolution radar, premium lightning, and satellite layers built for serious weather tracking.
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Clothing Suggestion Tool
Get outfit suggestions matched to temperature, wind, rain, and activity level.
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Temperature Converter
Convert between Fahrenheit, Celsius, and Kelvin instantly.
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Pressure Tendency Calculator
Calculate 3-hour barometric pressure tendency from rising or falling readings.
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Weather App for Gardeners
Track frost risk, rainfall, and growing conditions for planting, watering, and harvest decisions.
City Guide
Lake Tahoe Weather Alerts
Winter storm warnings, mountain snow timing, and pass conditions for the Sierra.
Frequently Asked Questions
When does winter start in 2026?
What is the difference between freezing rain, sleet, and snow?
What is the difference between a Winter Storm Watch and Warning?
What is a Winter Weather Advisory?
What replaced the Wind Chill Warning?
What is wind chill and why does it matter?
What is a snow squall?
How accurate are snow forecasts?
When should I avoid driving in winter weather?
Will El Niño affect winter 2026-27?
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WeatherAI for Commuters
Plan winter commutes with hourly forecasts, radar, and storm timing.
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Emergency Preparedness
Get winter storm warnings, blizzard alerts, and ice storm notifications.
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WeatherAI for Canadians
Environment Canada alerts, extreme cold warnings, and winter storm tracking.
More Seasonal Guides
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Tropical timing, categories, cone basics, and preparedness planning.
Seasonal Guide
Severe Weather Season Guide
SPC outlooks, watches vs. warnings, and storm safety beyond tornadoes.
Seasonal Guide
Tornado Season Guide
Peak timing by region, warning signals, and tornado safety planning.
Stay Ahead of Winter Weather
Download WeatherAI for snowfall in your daily forecast and official winter storm alerts for the places you care about.