Meanwhile, in the South, there's an elevated flash flood risk in Alabama, Georgia and Tennessee, where scattered showers and thunderstorms are forecast for Saturday afternoon. Strong, slow-moving thunderstorms could drop rain at 1 to 2 inches per hour.

Wildfire smoke from Canada is blanketing the skies in the Midwest, leaving millions with dangerous breathing conditions.

The smoke is expected to remain over the northern and central Plains of the United States for the next couple of days, according to meteorologists.