You lose the most body heat from your head, so while you're riding on cold fall days that call for rain, use Castelli's Tempesta Cap to keep water out and heat in. Castelli constructs the hat with its proprietary eVent fabric, which is completely waterproof and doesn't release much heat, so it functions best on days when it's chilly and wet. The cap looks like a traditional cycling hat from the front, with a small visor to keep rain from getting in your eyes, and a flap extends down the back of your neck to keep cold raindrops from making their way down your back as you're riding. Visibility becomes more important as the days get shorter, so the Tempesta cap includes reflective trim along the back to help motorists navigating dark, wet roads see you easier. Fully sealed seaming throughout this hat makes it completely waterproof, and with a sleek design that fits under your helmet, it's something you won't be embarrassed to be seen in while you're warming up with a coffee after your ride.