The “old” Beetle convertible was last sold in the US sometime in the mid 70’s. They had lousy heaters, and were OK then but by today’s standards are pretty primitive cars.
Skip the old Beetle in favor of the modern Beetle selling new today. The convertible version has a good top that is nicely padded and insulated so driving it in the winter is not a problem at all. The new Beetle has a great heater and good A/C as well. Driving in the winter in NH is not a big deal. Some natives swear that the all season tires that come on the car are fine in winter, and other natives feel you’ll need snow tires. You can get the car now, enjoy it in DC for awhile and make the decision for or against snow tires after you relocate to NH.
At 59 you’ve waited long enough. Get the car you want and enjoy it! I’m 60 and I have a T’bird convertible and it I enjoy it, viva la convertible.