As of 2 pm, Hurricane Joaquin is now considered a dangerous category 4 hurricane with winds of 130 mph battering parts of the Bahama Islands. The latest projected path keeps it off shore, although there is still a lot of range in what the models are predicting. However, the strong flow around the storm directing moist air onshore in the Carolinas, combined with an upper-level low and a stalled front, has raised the potential for flooding in these areas tremendously.
The second image below shows the predicted rainfall in the US from now until Monday morning. Much of South Carolina and surrounding areas may get a foot or more of rain on top of already saturated soils, which will cause local flooding and has the potential to down many trees, affecting power. On the second image you can see that in this particular model, the hurricane itself stays offshore (that is the stripe of higher rainfall in the Atlantic Ocean). So just because the hurricane does not come on shore it does not mean that there is nothing to worry about.
Note that the official forecast from the National Weather Service in the third image has somewhat lower accumulations than the model output but still shows several inches of rain over the area.
Update at 3 pm from the NWS: Here are three different model results of rainfall–all indicate a significant flood event.