Unless you have a decent jacket (eg. just the right amount of coverage, but still has places to
breathe), then just count on being totally soaked.  To that end:

    - wear shorts, or tights, or otherwise one of those workout pants that somewhat repels water  (Konrad has a pair)

    - wear contacts (granted, the helmet will keep your glasses from getting very wet, but it's
      still definitely at least a little safer to wear contacts, especially if it really starts
      pouring)

    - if you're commuting, take a spare shirt to change to when you arrive, because, either way, it
      WILL BE SOAKED  (wearing a cheap jacket or not doesn't matter...  with one, you'll soak your
      normal clothes in sweat...  without one, the rain will soak them)



Oh yeah...  flying through the forest, with wet leaves on the ground*, in the dark, at 18+mph, is
about the closest thing I've found to rally car racing.  Woohoo!  You're CONSTANTLY trying to figure
out the tree-line as far ahead as possible, while simultaneously trying to take the best line
through the current corner, and having to worry about traction wherever you're at.  Terribly fun,
and it'll only get more fun the faster I'm able to go!

    
        * it was autumn when I first did this.




==== random notes ====

- I rode in 63 degree weather with my Aerostich motorcycle jacket, with the armpit and back vents
  completely open...  I was at a comfortable temperature, though my shirt got TOTALLY soaked. still. still.