Valencia oranges - often called summer oranges-are actually available from February through October, with peak supplies in May, June and July. Valencia oranges may have a few seeds and are usually thin-skinned. Even though the fruit is deliciously sweet and completely ripe, Valencia oranges may occasionally "re-green" in warm weather. When the fruit ripens on the tree, it turns a bright orange color, as usual. But the warm temperatures of the season may make the skin reabsorb chlorophyll as it hangs on the tree, causing a ripe orange to look partly green. A “re-greened” Valencia is typically very sweet.