Some areas could see up to 8 inches of rain, prompting warnings affecting millions of people over the next few days.

"Flash flooding is ongoing or expected to begin shortly," the National Weather Service warned.

Here are some locations to avoid because of high water risks, according to Houston Transtar: The flash flood warning from the National Weather Service was issued at around 12:40 p.m. and stated that rainfall amounts of 2 to 4 inches per hour were expected in some parts of the county.