+1. People also need to take into account whether the temperature is supposed to rise during the ride and, if so, by how much. I have seen far too many people on club rides dress to be warm standing around in the parking lot. 15 minuntes into the ride they are sweating like pigs and end up having to cram extra layers into their pockets or wrap them around their wastes.

A few weekends ago I did a 75 mile ride with some decent climbing in places. It was about 36 degrees a foggy when we left the hotel. The predicted high was around 59 and the fog was supposed to burn off within the hour. I knew there would be some sunny areas along the route, but also a lot of riding in the shade. I wore shoe covers, bibs, a Rapha base layer, arm and leg warmers and a light jacket. On my hands were Polypro glove liners, a thin pair of full fingered gloves and a final, mid-weight pair of full fingered gloves. I was cold when we started out, but by about mile 10 the jacket came off because the sun was higher in the sky and the fog had lifted. I ended up being comfortable for the rest of the ride, and the only other thing that came off were the leg warmers with about 15 miles to go.