San Clemente, Calif. offers some of the finest weather in the world. With mild summers and winters, you'll never need winter coats and boots, though they can be fashionably cozy.
The weather is described as Mediterranean, which means there's seldom any rain, and not much humidity either. If you plan a visit to San Clemente, the ocean temperatures are best around July and August, though the summer extends into September, October and early November, as well.
June Gloom is a condition where it looks like it could rain, though it rarely does. The day is overcast (and usually cool) and you may see sunshine break through the clouds around 3 to 4 p.m. in the afternoon, just before the sun begins to fade.
If you are looking for the maximum opportunity to visit San Clemente, you really can't go wrong any time, though tourists prefer the months of April through September, then December through February when they seek to escape the Eastern cold.