St. Louis, Missouri – A colder push of air sliding into the Midwest ahead of St. Patrick’s Day could turn part of an active storm track into accumulating snow across eastern Missouri and much of Illinois between March 11 and March 17.
According to the National Weather Service Climate Prediction Center, Missouri and Illinois both fall within a 40-50% probability zone for above-normal precipitation during the 8-14 day period. At the same time, northern Missouri and much of Illinois trend near to below normal on temperatures. That overlap increases the likelihood that stronger systems produce measurable snowfall, particularly during overnight and early morning hours.
In the St. Louis metro area, including St. Charles County and communities along the Metro East in southwestern Illinois, nighttime lows dipping into the upper 20s and low 30s could support slushy accumulation on grassy surfaces and untreated roads if moderate precipitation develops. Along Interstate 70 from Columbia, Missouri, through St. Louis into Effingham, Illinois, bursts of heavier precipitation before sunrise may briefly reduce visibility and create slick stretches on bridges and overpasses.
Farther south toward Cape Girardeau and Carbondale, rain is more likely during daylight hours, but brief rain-to-snow transitions remain possible at night if colder air deepens.
Drivers across eastern Missouri and Illinois should monitor early morning travel conditions closely. Even light late-season snow can create hazardous roadways. Additional updates are expected as the March 11-17 window approaches and confidence in storm timing increases.
