Originally Posted by
cyccommute
Looking at the posts that have locations, all of you are on coasts or at low altitudes. I'll provide a perspective from higher up. I've ridden in most of the rest of the country and I can attest to the difference. I have a rain jacket and pants at work (I actually have 3 rain suits at work which I loan out). At 5000 feet, there is no such thing as a "warm" rain. When it rains here the temperature drop can be on the order of 20F to 40F. Even after storms, the temperature can take a while to recover. A comfortable ride goes to hypothermic ride in a hurry so it is prudent to have proper foul weather gear.
You don't have to be at altitude to get cold rain, and see temperature drops of 40°, though it helps. I've gone from sweating a climb in 80°+ heat to descending in a cold mist where ice crystals would form in the hair on my legs. Likewise I've led rides where we prepared for hyperthermia, and ended up treating hypothermia.