Hurricane Sally is predicted to dump up to two feet of water and deliver a storm surge of up to 11 feet on Gulf Coast states, according to the forecast.
Safety and health experts say residents should prepare for massive flooding that could lead to both short- and long-term hazards to their health and property.
ABC News' chief medical correspondent Dr. Jennifer Ashton, who was on the ground in Houston after Hurricane Harvey in 2017, said the floodwater dangers she witnessed there included drowning, electrocution from downed power lines, and infection.
Muddy, opaque floodwaters can hide large or sharp objects dislodged during a storm that can lead to injury -- "anything from a fracture to a major laceration," Ashton warned.
Floodwater may also contain snakes or other wildlife, human waste from overwhelmed sewage lines, and chemicals leached or spilled from flooded sites.
Stagnant water is a paradise for bacteria, and any open wounds give bacteria a way into the body. That can lead to anything from a simple soft-tissue infection to a much more severe infection. People with a weak immune system are most vulnerable.
Here are a few commonsense strategies to help avoid unnecessary risk from floodwaters:
Before flooding, look up your neighborhood's flood zone and determine if your home or business is prone to flooding. Come up with an evacuation plan and make sure your car has a full tank of gas. Stock up on non-perishable foods.
After flooding, ensure your drinking water is sanitized and wash your hands thoroughly after contact with floodwaters. Disinfect objects that have come into contact with floodwater before offering them to children or toddlers.
Try to avoid exposure with floodwaters for long periods of time to prevent physical injury. Wear waterproof boots if you have them. Do not attempt to drive over flooded streets as it could damage the car and strand passengers.
Keep any open wounds clean, dry and covered if you must go through the water. Seek medical attention for any wounds that are not healing or are festering or making you feel ill.
If you come to a stream where the water is above your ankles, stop and seek higher ground. Six inches fast-moving flood water can knock you off your feet, according to safety experts.