I have several black jerseys and one brown jersey I wear through most of the summer in rotation with lighter color jerseys (white, light blue, highlighter yellow). I also rotate between three helmets (white, blue and white, and dark grey and green) Most summers, it doesn't get too hot here in Wisconsin, maybe into the high 80s in mid July through mid August. But just as often, it is more like low 80s or even upper 70s near Lake Michigan, so jersey and helmet color usually isn't too great a concern. That said, on days where the temps go above 90 degrees, I usually go with a light colored jersey and the white helmet. Probably just a mental thing, though.