I had mild hypothermia hiking in July in the mountains of VT a few years back. It was cool, and raining. I started warm enough. The plan was to meet up for lunch (my hiking partner is an easy foot taller than me), then continue on to the shelter for the night. the place where we were going to have lunch was a nice shelter, about 4 miles from where we were-a nice overlook of the towns. Then, after lunch, continue down into the valley, up another mountain, where there was another shelter 3 short miles away from our lunch spot.
Well, it started off rainy-I decided to just hike in shirt & shorts, as putting raingear on I would get wet anyway. I got chilled real fast. I remember sitting down, being cold, and not really thinking that putting something on would be a good idea. I then got up & started hiking BACK the way I came. I ran into hikers I had seen earlier, and they turned me around. I convinced them that I was OK, they went on ahead. This whole time it was STILL drizzling, and about 40. I got to the point that the only thing going through my head was what I wanted to do; get to the shelter, strip, start stove, huddle in sleeping bag, drink soup. This became my mantra. I could no longer feel my hands, and, deep down, I knew I may be in trouble.
I FINALLY got to the shelter-and didnt have any fine motor skills to start my stove. I huddled, in a corner, out of the wind, under my sleeping bag. My partner, who started later than I did by an hour, fortunately came withing 20 minutes or so, got my stove started, and I got warm. That was the scariest moment I ever had-I didnt really have control of the situation at that point, and, although I was on a well marked trail, in a shelter, and potentially people would be by before I got too much worse-I didnt have the wherewithall to make competent decisions.