Rick's comment about the exposed areas is important. Last time we did it, we drank almost all the water we had in our packs, at least three liters for the adults and two for the kiddo. This was on a day that was cool by STJ standards.

I remember the steepest part of the trail being at the top at the Centerline trailhead. If you are coming up from the bottom, you aren't missing anything by skipping that section.