I've seen wet snow down to the town in early August before. It was when i was living in bishop and i saw a neat storm to the northeast. Thinking there might be a good thunderstorm and noticing that it looked a bit different from the normal summer storms, i decided to drive after it. Up by convict lake i noticed some white streamers of precipitation against the mountains which i thought was odd, but assumed was probably just hail. But anyway upon arrival to Mammoth there was snow all the way down to 7000 feet. It was wet and melting fast but up by the lakes there was an inch or two still there. The difference between the freezing air and the summer-warmed lakes was causing all kinds of steam to rise up off the water... it was really amazing. But the moral of the story is.. NEVER go into the high sierra without being prepared for snow. I've seen snow falling higher up just about any time of the year.. july 4, august, you name it. They have also had rain falling up to 12,000 feet in janurary... warm rain falling on 20 feet of snow makes a hell of a flood. And sometimes a thunderstorm will come over a ridge and literally change the weather from warm and sunny to half inch hail and crazy lightning in about 5 minutes Mountain weather is crazy.. be ready for anything.