I've never been fortunate enough to hike the main Whitney trail with a full moon.

I'm wondering how much light -- assuming that there's a reasonably cloudfree sky -- I might expect hiking one day away from a full moon this year. I'm assuming that I'll still need the light of a headlamp, yes?

There will be little difference on the night before or after a full moon as far as light. This is assuming there is no cloud cover.One probably could get by most areas with the light of the full moon but there must be dark shadowy areas that will not be a recipient of the full moon light due to trees and Mtn ridges.A lot would depend on the time of night and where you are on the trail. I would definately have a headlamp close by no matter what.Just because there is a full moon which can be counted on doesn't mean it will be clear of clouds which cannot be counted on.

Hi Mike, I hiked last year on a full moon and it kind of depends where you are on the trail and the time you leave. I started at 3:00 A.M in early September. I needed the headlamp for the first three miles or so. But once I got to the logs that cross the creek before Lone Pine Lake, I turned my lamp off for a few minutes to just ingest the wonder of the full moon, the illumination against the granite peaks and the wonderful shadows coming through the trees. For the next mile or so, I just kept playing with the lamp and turning it off from time to time. If you are hiking during a full moon, just make sure you're on stable ground and enjoy the beauty of the Sierra's at night. I cannot express how beautiful it was.

It really depends. The moon sets behind the mountains at some time during the hike. I came up from Guitar Lake and moon must have set 4 or 5 times behind Mt. Hitchcock on the way up to Lower Trail Crest.

To be honest, I prefer hiking during a new moon, which I've done twice.

Hi, MikefromMD

I prefer the waning gibbous. The moon rises later in the evening (early morning).

Headlamp? The trail is clearly visible from the TH to Mirror Lake. Above ML there are a couple "wait-a-minute-where's-the-trail" spots requiring the use of a headlamp.

After that proceed to the summit!

Have fun.