Hurricane Harvey is heading toward Texas and is set to make landfall late Friday night or early Saturday morning -- meaning that people should take preventative measures now.
"Tomorrow will be too late," National Hurricane Center (NHC) spokesman Dennis Feltgen told Fox News on Thursday. He said that people ideally should have made preparations by June 1, which was the start of the Atlantic hurricane season.
People should prepare to have one week's worth of food and water for each individual in a family, as well as enough of any medicines that are needed, he said.
Feltgen also advised that people board up their houses.
People told to evacuate should be aware of their local evacuation routes and have a plan in place for staying somewhere, the Ready.gov website advises.
It recommends assembling a bag that contains "a flashlight, batteries, cash, first aid supplies, medications, and copies of your critical information if you need to evacuate."
"If you are not in an area that is advised to evacuate and you decide to stay in your home, plan for adequate supplies in case you lose power and water for several days and you are not able to leave due to flooding or blocked roads," the preparedness site says.
Ready.gov advises that when the storm is 18-36 hours away, people take in "loose, lightweight objects" like trash bins and trimming trees which could hit buildings.
If a hurricane is closer -- 6-18 hours away -- people should check their city or county website for updates in half-hour intervals, and should charge their cell phones to be ready if there's a power outage, according to the site.
There are also tips for when the storm is just 6 hours away.
In that case, the site suggests that people who aren't in an evacuation-recommended zone stay put and tell others about their location. Other tips include putting refrigerators and freezers on the coldest option, and avoiding windows.
On the road
The Federal Emergency Management Agency (FEMA) has warned about potential flooding dangers for drivers. The agency said in a Thursday news release to look out "for flooding in low lying areas, at bridges and highway dips."
"If you encounter floodwaters, remember – turn around, don't drown," it stressed.