Head northwest on Minaret rd from Mammoth Lakes to the ski resort. From there take a bus to the Devil's Postpile Trailhead.
Early season is best to catch the ice in the lake.
Not a cloud in the sky at that moment or for the rest of the morning but it didn't bother me much at all. Light and shadow is all you really need in a place like this. About 90 percent of the time I've spent backpackpacking the Sierra there hasn't been a single cloud out at sunrise, when it does happen your lucky.