Authorities have opened emergency operations centers in Texas, moved inmates to prisons deeper inland and passed out sandbags.
A Home Depot in Brownsville ran out of its supply of plywood Sunday as people rushed to board up windows. Other customers crowded the store scooping up batteries, generators, water and flashlights.
The head of FEMA says up to 100,000 people might have to evacuate the southeast Texas coast if Dean shifts north toward Brownsville. Right now, forecasters say it's on course to strike northern Mexico Wednesday.
Meanwhile, Dean is gaining strength. The National Hurricane Center says the first hurricane of the Atlantic season could reach the highest level, Category 5, later Monday.
It has killed at least eight people as it moves across the Caribbean. Jamaica avoided a direct hit but the storm still uprooted trees, flooded streets and tore the roofs off many homes and businesses.