Emergency rain gear.

[Pferox]

I always keep a few 30 gallon garbage bags in my tackle box.
When I get caught in the rain unexpectedly, a few holes and you have an adequate poncho, to stay dry.

[nlareau]

Went to Niagra falls a few years ago, took the Maid of the Mist ride.  Leaving the boat everybody was throwing their ponchos in the trash.  I grabbed a handful and carry them in the boat.  It might look stupid in a blue plastic bag with "Maid of the Mist" printed on it, but they have hoods, long sleeves, and you can't beat the price.