The latest chapter in trying to figure out what to do if one is caught in the rain is a new paper out in Eur. J. of Phys.
Basically, the best strategy for staying dry (or at least somewhat dry) is to run as fast as possible. Unless you’re really thin, in which case there may be a more optimal speed. And if you’ve got a tailwind behind you, then you should run exactly as fast as the wind at your back.
So the answer is, it depends! It depends on the body shape, the wind direction, etc... etc. There isn't one single answer that's applicable to all situations, which to me, makes sense.
So there! Who cares about those damn Higgs bosons? We need to find out how not to get wet in the rain! :)
 F. Bocci Eur. J. Phys. v33, p.1321 (2012)