St. Louis, MO – Gray skies stretch over the Mississippi River this morning as colder air rushes into eastern Missouri and southern Illinois. The calm before the storm won’t last long — a developing winter system is set to sweep through late Friday, bringing snow, sleet, and slick travel across the St. Louis metro by Saturday.
According to the National Weather Service in St. Louis, a Winter Weather Advisory will go into effect from midnight through Saturday night for much of the region, including St. Charles, Alton, and Edwardsville. Forecasters expect 2 to 4 inches of total snow, with a mix of rain and sleet possible early in the event. Drivers should expect slippery roads and reduced visibility, especially along Interstate 70 and I-55, where road crews may struggle to keep up with the changing precipitation.
The system begins as a cold rain late Friday before transitioning to a rain-snow mix by early Saturday morning. Temperatures will hover near freezing through the day, making any untreated roads or bridges prone to icing. Winds gusting up to 25 mph could create patchy blowing snow and limited visibility in open areas.
Sunday turns calmer and colder, with highs only near 30°F and partly cloudy skies. Looking ahead, a reinforcing shot of Arctic air is expected to drop into the Midwest by midweek, bringing the first true December cold snap of the season.
5-Day Outlook (St. Louis, MO)
Friday: Increasing clouds, high 39°F.
Saturday: Rain and snow mix, 2–4″ possible, high 39°F.
Sunday: Mostly cloudy, high 30°F.
Monday: Slight snow chance late, high 28°F.
Tuesday: Partly sunny, high 31°F.
