We spend a week at Dillon Beach every year over New Years. The weather is beautiful, even when it is drizzly or rainy. As long as you don't mind getting wet from time to time, the temperatures are great. Summer is my wife's busy season, so we don't get much time to camp unless it's fall/winter. We love camping on the Coast in the dead of winter, and often leave the snow at home as we head to the 'warmer' coast.
It's mostly light jacket or sweatshirt weather, but there have been plenty of times I'll spend the day in shorts and a T-shirt in late December on the coast.