You need to build up your mileage gradually. You should try to get up to 60 mile rides at the latest the month before, then if you can ride about 75 miles or so two weeks before you should be OK. So start with 15-20 mile rides and work your way up. But you should get started pretty soon. I don't know where you live but here on Long Island New York we get snow in the winter. I rode at every weekend last year and hope to do the same this year. If it is cold you dress in the proper clothing. Check the winter forum.