Harold made landfall on Padre Island, Texas, Tuesday morning as a tropical storm, bringing heavy rain and strong winds with it.
Harold weakened from a tropical storm to a tropical depression later on Tuesday afternoon.
Most areas are forecast to see 2 to 3 inches of rain but isolated areas could see 6 inches.
In Corpus Christi, rainfall rates could reach 2 inches per hour.
"The good news is that the bulk of this rainfall will be beneficial for the drought-stricken region, but too much rainfall too fast could lead to isolated to scattered instances of flash flooding," the National Weather Service Weather Prediction Center said.
Conditions will improve Tuesday evening as Harold weakens and moves inland across Texas.
All tropical storm warnings have been discontinued but flood watches remain in effect in the western part of the state where heavy rain will hit on Wednesday.