Hike started with a light but steady rain, then long stretches of nothing until just after 10, when intermittent snow showers began.  By about 1130, it was now snowing hard and steady. It was calm for another hour or so, just long enough for us to reach the summit, but then a huge snow storm hit, including some thunder, that forced us to hunker down in the doorway to the visitor center.  Of course it would be closed today, so we were forced to wait it out.  Luckily it only lasted 5 minutes or so, then the skies cleared up long enough for us to make it back down to the car.  This was now officially my favorite hike up Mount Diablo!