January has been the very opposite of the mild December residents of northern Illinois experienced.

The flip of the calendar to a new year has brought out “the real winter” Illinois natives expect: snow, ice, cold winds, bitter temperatures, tough driving conditions.

Before a winter storm and extreme cold moves into northern Illinois, it is good to know these terms, according to the National Weather Service.

Watches, warnings and advisories

Winter Storm Watch

Issued for potentially significant winter weather, including heavy snow ice, sleet, and/or blowing snow within the next day or two. Prepare right away.

Winter Storm Warning

Indicates heavy snow, blowing snow, sleet or a combination of winter weather hazards are expected to cause a significant impact to life or property. Stay indoors and adjust travel plans.

Winter Weather Advisory

Snow, blowing snow, ice and/or sleet is expected to produce potentially dangerous travel conditions within the next 12 to 36 hours.

Blizzard Warning

Strong winds (35 mph or greater) will produce blinding snow and near-zero visibility, resulting in potentially life-threatening conditions, particularly for travelers. Blizzards can occur with minimal snow accumulations.

Snow Squall Warning

Sudden whiteout conditions with near-zero visibility and flash freezing of road surfaces resulting in potentially life threatening-conditions for travelers because of bursts of heavy snow in a localized area.

Ice Storm Warning

Heavy accumulations of ice are expected to cause a significant effect on life or property, resulting in hazardous travel conditions, tree damage and extended power outages.

Wind Chill Warning/Advisory

Warning comes with wind chills are at life-threatening levels of minus 25 degrees or colder. Advisory comes with dangerous wind chills of minus 15 degrees to minus 24 degrees.

Winter weather terms

Freezing Rain

Precipitation that falls from the clouds as rain, but freezes into a glaze of ice on ground-based objects (such as trees, power lines, roads and cars.)

Sleet

Small pellets of ice created by frozen raindrops. Sleet bounces when hitting a surface and does not stick to objects.

Wind Chill

A calculation of how cold it feels outside when the effects of temperature and wind speed are combined. Wind chill only applies to bare, human skin. The effects of wind chill are different for animals and don’t apply to nonliving objects.