Steve, I went up Whitney last Memorial Day weekend, which is when Whitney supposedly became "doable" for those without special equipment. While there were plenty of success stories (which is what people tend to remember or focus on), there were also a far number of turn backs, stuck people, minor rescues, major rescues, and injuries both minor and serious. There was a fair amount of snow and ice. This was my first person view.
People ignore the following all the time...never go higher than you can safely descend.
Most of us who go out in the winter see it all the time during the fourth season.
Summit fever...don't catch it.