Recipe for Hypothermia

Take one cyclist in early season form.
Dress in spring -- not winter -- clothes (tights, wool shirt, cotton socks, rain coat, thin full-finger gloves, mesh shoes)
Ride due South for 2 hours in dry but overcast 35 degree weather
Now add heavy, cold rain, soak thoroughly.
Mix in hail, sleet and strong winds.
Ensure rider is completely soaked.
Add more rain.
Turn rider around and allow to ride to almost three hours into a 2o MPH wind to get home.
Watch as rider shivers so bad he shifts gears uncontrollably while trying to hang onto handlebars.
Upon arriving home place rider (fully dressed) in warm - not hot - shower for up to one hour. Listen for howls of pain as "pins and needles" rack rider in pain.

It helps that rider has been riding all winter on a bike with fenders so was unprepared for amount of spray riding new (fender-free) bike.

Mmmmm... Nice.