Most of us tend to only get soaked once; you will remember to stand back a little next time it's been raining.
I found a fix on e-bay, an umbrella hat. They're about 12" diameter and fix directly to an elasticated band around the head. They come in all different colours so you can match your paint. I got a comouflage one, put it down and now I can't find it.
http://www.ebay.co.uk
Item 130056926139 or 130054116011
Don't forget to post a picture of yourself if you buy one.