I once did a ride something like this -- it was 82 miles; an "end of season" ride for the local bike club, about this time of year.
It practically killed me - the weather had been difficult for several weeks, so I hadn't been riding much, and it was going to be my longest ride of the year. The day of the ride dawned nice and comfortable, but it got cold and blustery during the ride. I lingered too long at rest stops, and the ride just seemed to stretch out forever. I hated it, though was glad I eventually finished it. If it had been a century, I would not have finished.
The lesson I learned? On days with bad weather I will still ride but *well within* my comfortable mileage (example: last Saturday I wanted to do 40 miles or so, but it was raining, so I waited for the day to warm up a bit, and did 20...still better than sitting around at home).