Not normally. Rain is infrequent where I live and usually quite warm when it happens so a ball cap at most if the forecast calls for it. Though I have a set of frog toggs in my Wrangler, just in case since I'm top down most of the year.

I get more concerned with cold, than wet. It's easy to be lulled into weather ambivalence living in the Sonoran Desert. You figure if its sunny and hot here, it is everywhere and neglect to pack base layers and puffy coats for when you get off the plane and its 60 degrees colder. So I 'try' to always look at destination forecasts and then believe it will be worse.