ILLINOIS — Heavy snowfall events producing a foot of snow or more in a single storm are uncommon in Illinois, but historical weather data show that such events are possible in January under the right conditions.
Illinois lies in a region where Arctic air from Canada can collide with moist air from the Gulf of Mexico, a combination that can support significant winter storms.
In January, cold air is often firmly in place across the Midwest, allowing precipitation to fall primarily as snow when strong storm systems move through. When these systems slow down or intensify while tracking across or near the state, prolonged snowfall can occur over a relatively small area.
Past records from the National Weather Service show that several January storms have produced snowfall totals of 12 inches or more in parts of Illinois. Northern Illinois, including the Chicago area, has experienced multiple single-storm snowfalls exceeding a foot, while central Illinois has also recorded similar totals during major winter systems. Southern Illinois, while generally warmer, has occasionally seen heavy snow when temperatures remain cold enough throughout the event.
These high-impact snowfalls typically result from strong low-pressure systems that draw large amounts of moisture northward while cold air remains locked in place at the surface. In some cases, bands of heavy snow can persist for hours, leading to rapid accumulation. Lake Michigan can also enhance snowfall in northeastern Illinois when winds align favorably, further increasing totals in localized areas.
While a foot of snow in one January storm does not occur every year in Illinois, historical climate data confirm it is within the state’s range of winter weather extremes. Such events are part of the long-term weather record and demonstrate how Illinois’ geography and seasonal climate can occasionally support very heavy snowfall from a single winter system.
