The National Weather Service is predicting scattered thunderstorms late Friday afternoon into the evening in the St. Louis area.
The best chances for thunderstorms are between 4 and 8 p.m. near the Interstate 70 corridor. The forecast covers parts of eastern and central Missouri and west-central and southwest Illinois.
Forecasters don't expect severe storms but say an isolated strong storm is possible, bringing heavy rains and wind gusts up to 40 mph.
Before any storms move in, the National Weather Service said the region will see clouds increasing with a high near 94 degrees on Friday. Winds are in the 5 to 7 mph range. Forecasters put the chance of showers after 4 p.m. and before 11 p.m. at 50 percent.