While it is very good style to drive a two-seater roadster, you do not - I repeat DO NOT - confine your top down driving to summer months. That is disgustingly middle class American and makes you look like some jerk in a Viagra ad.
No, you continue to drive top down when the temperature is down into the 40's - and even the 30's if you have gumption.
Of course, you would invite pneumonia should you drive top down exposed. You substitute clothing for cover. Essentially, you are driving in an open cockpit.
The solution is to wear a leather flight jacket. While you could choose from several good styles, a good solution - arguably the best - would be to choose the traditional WWII Army Air Corps A-2. Think Steve McQueen in The Great Escape. Think Colonel Hogan of Hogan's Heroes.