I got the ASICS Unisex Adult Storm Shelter Cap (same hat, but in black) in time for my 10k race but thought the weather was going to be "too" nice to wear it. Then I remembered that I run in Kansas.
Race Day was 40 degrees and dropping with rain, turning to sleet in the last mile. When I got back to the car, every part of me was dripping, except my head. The cap did a wonderful job of keeping my head warm and dry, both by blocking the wind and the rain. (There were also wind-gusts of 10-15 mph during the race.)
I was looking for a good hat to wear during the winter and during rain storms to keep myself warmer and drier and I have definitely found it.
I'm pretty sure that this cap would warm me up too much during the summer months, but that's okay. If it's raining in July, then there's a good chance I might actually be comfortable with a wet head.
I'd definitely recommend this cap to anyone looking for a good rain hat.
Update 8/13/13: I've worn this hat in the rain several times since last November. I also wore it throughout the winter to keep my head warm. It always does a good job keeping my head dry (and warm) when needed. And as I expected, it is a warm during the summer, even when raining.