The hurricane, which has claimed some 70 lives in Haiti, is expected to strengthen to at least a Category 3 storm on the Saffir-Simpson scale before it reaches the U.S. coast, with wind speeds of up to 180 km/h (111 mph).
"Persons not heeding evacuation orders in single-family one-or two-story homes will face certain death," the U.S. National Weather Service said in a statement. "All neighborhoods ... and possibly entire coastal communities ... will be inundated during the period of peak storm tide."
Four counties in the state, which is home to 24 million people, have started mandatory evacuations. Most of the evacuations were carried out near Houston and Galveston Bay.
Around 1,300 buses, as well as ambulances and other paramedic vehicles will be used to evacuate residents from coastal areas. The hurricane has also forced the evacuation of over 1,300 prisoners from the Texas Correctional Institutions Division's Stevenson Unit in Cuero.
The storm is expected to make landfall on Friday night.
Ike is the third major hurricane in this year's Atlantic hurricane season. Earlier this month, Hurricane Gustav swept through the Caribbean, leaving 120 dead. Hurricane Hanna caused deadly flooding in northern Haiti last week, killing 536 people.
