It is going to be 27F tonight. Top up. I have noticed over the years that new owners of roadsters tend to push the edges of the envelope. I am driving my third convertible and so I don't feel the need to risk frostbite by top down driving when the weather is very brisk. But, I have also noticed that other owners drive around with tops up on perfect days. If it's 78F and sunny and you have your top up, what are you waiting for? Fool, this as good as it gets. Maybe it's a concern about hairstyle and wind.