Nicholas could dump up to 20 inches (51 centimeters) of rain in parts of central and southern Louisiana.
Greg Abbott said authorities placed rescue teams and resources in the Houston area and along the coast.
Six to 12 inches (15 to 30 centimeters) of rain were expected along the middle and upper Texas coast, with isolated maximum amounts of 18 inches (46 centimeters) possible.Other parts of southeast Texas and south-central Louisiana and southern Mississippi could see 4 to 8 inches (10 to 20 centimeters) over the coming days.
Nicholas brought rain to the same area of Texas that was hit hard by Harvey.That storm made landfall in the middle Texas coast then stalled for four days, dropping more than 60 inches (152 cm) of rain in parts of southeast Texas.