The National Weather Service has issued a freeze warning for the Chicago area.
The warning is in effect from midnight to 8 a.m. Saturday for Cook, DuPage, McHenry and Lake counties.
"Sensitive outdoor vegetation will be at risk. Take the necessary precautions to protect your sensitive plants," read the warning.
Saturday temperatures are expected to be in the upper 40s and lower 50s. Things aren't expected to warm up all that much for Sunday's Bank of America Chicago Marathon.