I also just got back from a hike this weekend, and you're absolutely correct about the weather aspect. It's amazing how many people are unprepared for weather extremes.

For example, I was out hiking this weekend. My destination was Palm Springs, in the middle of the California desert. When I arrived, it was 80+ degrees and a beautiful sunny day, most people were dressed for the beach, while I was packing along my rain gear and extra jacket. Took the tram to the top of the mountain, where the temperature was in the mid 40's and there was snow on the ground and ice on top of the puddles. Most people at the top were not very well equipped to just be standing there, let alone hiking. I ran across a few hikers that were dressed in shorts and sandals, and nothing else. During the hike, I had to give directions to a couple of people that didn't really know where they were. Even during the hike, I had considered turning around because the clouds had come in very quickly, the temperature dropped about 10 degrees, and it looked like it was going to snow. The only reason I didn't was because I knew I had enough equipment to spend the night out if I had to.

Even though the day started out nice and it's a fairly easy place to hike, with a lot of tourist and families, it's important to remember that things can change very quickly. Most people probably thought I was way overdressed for the short dayhike that we were doing, but I always carry enough to spend the night out if I have to. I had been backpacking at the same place less than a year ago, so I know how quickly the weather can change at that altitude, and how easy it is to get lost. Even two somewhat experieced hikers, with topo maps and compases, can get "misplaced" for about 4-5 hours before they find the right trail. If that had happened this last weekend, it's almost certain that we'd be spending the night out there in freezing temperatures, even though the day started out hot and sunny.