I assumed we would be above the cloud line, but I was wrong. The drive was difficult due to poor visibility - about 30 feet in rain and dense fog. It was also unnerving to see people on bike tours riding down the mountain in wet conditions, poor visibility, and limited experience (kids, moms, dads). We couldn't even see the visitors center from the parking lot. The top of the mountain was very cold and rainy too.
Advice for others - call ahead to check the weather for the drive up and at the top.