how are the temperatures going up lately? debating on what to wear exactly..
On the Whitney Weather page (link above on the left), there is a "Cottonwood Lakes, elev. 10150' 7-day Temperatures" link. It shows highs and lows there about 37 to 67 F. With temps dropping roughly 7F per 2k elevation, that puts Trail Camp at 30 and 60, and the summit at 23 and 53. These, of course, are rough estimates, no prediction of what you will find.
I would look at the NOAA forecast pages for another good prediction (links also on the Whitney Weather Page. ) NOAA forecast puts summit highs at 55-59, lows 30-38.