Springtime is for lovers, and it’s no coincidence that spring is when most love affairs with South Carolina  begin. Unless you have severe pollen allergies, you should try to experience this area at its peak of natural beauty during the magical period from mid-March to mid-May. Not surprisingly, lodging is typically at a premium at that time.
For those interested in South Carolina’s excellent state park system be aware that there are minimum stays for cabin rental, usually a week, during March–October. In the off-season this doesn’t apply.
June–October is hurricane season on the coast, with September in particular being the time of highest risk.
In Myrtle Beach  the high season is totally counterintuitive. Unlike the rest of the state, the absolute hottest months of summer make up the big season here—the better to enjoy the water, you see. Prices are higher and availability is lower during this time.
Golfers , however, will tend to see bigger crowds on the links as the weather cools—though Myrtle Beach’s oversupply of courses means there are usually tee times available and some good deals. In any case, starting about the middle of November you can find some very good prices on lodging in the entire Myrtle Beach area.
Under its metropolitan veneer, Columbia  is still very much a college town. Fall means football, and that means the most festive time of year. It also means the most competition for lodging, especially when the Gamecocks are playing at home. Summer can get really slow in Columbia. Hot, too. As much as I like Columbia, I advise avoiding it during summer if possible.
Aiken  has two big equestrian seasons. Most of March is taken up by the Triple Crown equestrian events, and October is big for tournament polo and steeplechase. Indirectly, April is also very competitive lodging-wise, largely because nearby Augusta, Georgia, hosts the insanely popular Masters golf tournament, with much spillover into Aiken.
The Upstate  is great most any time of year. Spring is best weather-wise, and while summers can get quite hot, there’s some real relief at night. Fall foliage scenery can be surprisingly glorious well into December.
While Columbia is Gamecock country, in the Upstate all things revolve around Clemson Tiger football. During fall home games, lodging is more difficult to find in a wide radius around Clemson, and rooms book early.
My favorite time of year in South Carolina , though, is the middle of November, when the tourist crush subsides. Not only are the days delightful and the nights crisp (but not frigid), but you can get a room at a good price.