Les,
I'm in the same boat. Even worse, since I'll be running the Rock N Roll
Marathon in AZ this Sunday. The forecast varies between a few showers
and showers all day, and believe me, when it rains here in AZ it's not
usually a drizzle, but hard rain. The temps are supposed to be around
low 50s all day.
While I've run a few shorter races in the rain, this will be my first
marathon in rain (unless we luck out and the weather clears). I did get
caught in a short downpour a few years ago while running the Disney
marathon.
Here's what I'm planning:
1. A big plastic garbage bag to stick my head through and wear as a
poncho until the race starts. We'll be in the corrals for about 1/2
hour and if it's raining then it will be really miserable since we're
not even moving.
2. A running hat with a long brim to keep the rain off my face.
3. A long sleeve shirt over a short sleeve shirt. I'll peel them off as
the weather (or I) warm up.
4. Gloves for before the race, and maybe into it as well.
5. But except for the start, I plan on running the race wearing what I
usually do - a singlet and shorts. Anything else will only get wet from
the rain (or make me too hot and sweaty if a Goretex type jacket) and
absorb and hold the water.
Good luck to you.