While the solstice (and shortest nights) will not occur for about another week, the earliest sunrises occur now. Why is this? Short answer: celestial mechanics. As for why the Sun doesn't have its extreme rise/set dates on the day of the solstice, it all has to do with solar noon, the point in time wherein the Sun reaches its highest point in the sky, which is the basis for the timing of the solstice. Problem: the Sun doesn't always reach its highest point in the sky as seen from Earth at noon. In contrast, the Sun is at its peak elevation about a week before the solstice in summer, which means that, solar noon being about 8 minutes before Earth noon, that also means that the sunrise occurs about 8 minutes earlier, too.