by AlmostThere » Sun Jul 08, 2012 4:39 pm
Check the NOAA website for Yosemite valley in the week leading up to the day you go for an accurate assessment of what it will be like.
Right now it is pushing 100F in the central valley and Yosemite Valley is frequently not much cooler. It's currently 96F at Happy Isles, according to NOAA, and I would not doubt it. The weather has been unusually cool for short periods, interspersed with our usual July heat.
Best way to do Half Dome is to get a very early morning start, get up the switchbacks as quickly as you can before it heats up.