Snowfall typically makes for tougher travel conditions and slower drive times, but Friday's snow in the Chicago area will mean something even worse for commuters.
As accumulating snow begins to cover area roadways, forecasters warn that salt won't be as effective as it normally is due to the brutally cold conditions.
"When temperatures get this cold, salt becomes much less effective," said NBC 5 meteorologist Pete Sack.
Salt is intended to lower the melting point of ice, but when temperatures dip below 20 degrees, that process can take as much as five times longer than it would when temperatures sit near 30 degrees.
That could prove to be bad news for some area commuters as a fast-moving winter system brings snowfall to parts of the area.
A Winter Weather Advisory has been issued for most of northeast Illinois and parts of northwest Indiana, warning of 3 to 5 inches of snow expected.
The highest totals are expected south of Interstate 80, though much of the Chicago area is expected to see between 2 and 4 inches. Areas far north of the city may only see between 1 and 2 inches.
DeKalb, Kane, DuPage, Cook, LaSalle, Kendall, Grundy, Will, and Kankakee Counties are all under the advisory beginning at noon Friday and ending at midnight Saturday morning, according to the National Weather Service.
Lake, Porter, Newton, and Jasper Counties in Indiana are also listed.
Timeline: What to Expect and When for Friday's Snowfall
The snow began falling during the late morning and early afternoon hours, spreading west to east before it is expected to end mid- to late-Friday evening.
The NWS warns that snowy conditions could make for difficult travel during the afternoon and evening rush hours.
"Given the cold air temperatures, expect roads to become snow covered," the NWS reports.
Temperatures stay cold Friday, with highs in the teens and wind chills near 0.