Despite the fact that this has been an unusually warm fall, we can assume at some point that it is going to get cold. Hypothermia can be a very dangerous condition if you are caught unprepared when temperatures fall and you have a long way until finding a nice warm place. It is surprisingly easy to get hypothermia. Cotton clothes and any sort of precipitation are a bad combination. Once hypothermia starts to set in, you'll notice a variety of symptoms including:
Building a fire is obviously a way to combat hypothermia but if you don't have the means or the time to do that, another alternative to warming up is to look and see what the animals around you are doing. The squirrel is an industrialist little critter that spends a lot of time collecting seeds and nuts but if you watch carefully, you'll notice him also collecting leaves. Look high up in the trees and you'll see giant bundles of leaves packed in around a nest. The leaves provide very necessary insulation for the squirrel. The squirrel nest is the inspiration to the debris hut that so many survivalists build but you can also use the knowledge to layer your clothes with leaves to stay warm too. So if you are walking along and start to shiver, just grab a bunch of leaves and start layering them inbetween your clothes. Word of caution though...don't put them against your bare skin!