The National Weather Service in St. Louis has issued a freeze warning for the area from 1-9 a.m. Wednesday.
Temperatures are expected to drop as low as 27 degrees during the warning, which covers the eastern part of Missouri as well as southwest and west central Illinois.
The cold temperatures could damage plants and unprotected outdoor plumbing. The National Weather Service advises residents to cover plants or bring them indoors.
Overnight, Tuesday into Wednesday, temperatures are expected to fall into the mid-20s, which will be near record low levels.
Temperatures Wednesday into Thursday are expected to be in the low 30s, again close to record levels.
Snow, mixed with rain, started falling in the area Tuesday morning. It is expected to change to all snow before mixing again with rain. Little to no accumulation is expected.