i've sent several people home for not coming to work prepared for the weather conditions. i'm not asking people to come to work in an ark or stuffed like the little boy in a christmas story, but keep in your car...rain gear, gloves, a fleece jacket and a stocking cap.
life in teh pacific northwest doesn't stop when it rains. infrequently, we'll get snow or super cold in the valley.
Wind breakers or rain suits block cold weather the best. Anything to keep the wind from the skin works best. Insulated work boots are very good to, but be sure they are Gortex® lined. Another thing people do is use thick socks which have the opposite affect, they cut off circulation. I go to the Army-Navy store and buy black military issue thin wool socks and wear those with the insulated boots. Use thinsulate® insulated gloves and a hood for the head and face. There are hoods that completely cover the head and face, they a work great. I have a Nomex® hood I use. Of course Duofold® insulated underwear work real good in very cold climates, for Alabama I would go with a cotton/poly mix. I have four different types of thermal underwear for different circumstances. These things worked up in Chicago/Toledo/Detroit in the winter, so it should work here. After about 1 month in the cold the amount of cold weather gear could be reduced as the body acclimates.
When I hit the road in 2000, in the middle of winter, I had to find out real quick what worked. Trial and error lead me to the advice I have given.