Winter Weather Terms

The National Weather Service uses the terms below to convey the weather threat to the public. It is important that everyone understands these terms and knows what protective actions need to be taken.

Winter Storm Watch
Indicates severe winter weather such as heavy snow or ice is possible within the next day or two. Prepare now!
Winter Storm Warning
Indicates severe winter weather conditions are occurring, imminent, or highly likely. Stay indoors!
Heavy Snow Warning
Snowfall of six inches or more in north and central Illinois, four inches or more in southern Illinois.
Ice Storm Warning
Heavy accumulations of ice will create extremely dangerous travel and damage trees and power lines.
Blizzard Warning
Snow and strong winds will combine to produce blinding snow, near zero visibility, deep drifts, and life threatening wind chill.
Wind Chill Warning
Life threatening wind chills of 25 below zero or colder.
Snow Advisory
Snowfall of three to five inches in northern and central Illinois, two to four inches in southern Illinois.
Winter Weather Advisory
Indicates winter weather conditions will cause significant inconveniences and may be hazardous, especially to motorists. Use caution!
Wind Chill Advisory
Dangerous wind chills of 15 to 24 below zero.
Freezing Rain Advisory
Light accumulations of ice will cause hazardous travel.
Blowing/Drifting Snow Advisory
Poor visibility and hazardous driving conditions.
Freezing Fog Advisory
Very light ice accumulation on roadways, bridge decks and overpasses, predominately from fog, causing hazardous travel.
Wind Chill
A calculation of how cold it feels outside when the effects of temperature and wind speed are combined.
Freezing Rain
Rain that freezes upon impact with the ground, creating a coating of ice on roads and walkways.
Pellets of ice, created by frozen raindrops. Sleet bounces when hitting a surface and does not stick to objects. An accumulation of sleet can make roads slick and hazardous.