"Gold medals are won in the winter, you just pick them up in the summer".
OK. How to do this? Conventional training means building your "base" miles - long, slow rides - hours of time on the bike - all about increasing your long-term endurance. Then in the spring you switch to shorter, more intense training to get your speed up and your hill climbing ability ready for that early season sportive.
Sounds good, but is super-hard to do. As the temperature drops, the daylight disappears and the rain comes in slant-wise that 2nd hour of slow riding looks less and less "fun".
How about doing something different? How about changing it around? Lets do short rides in the winter? Make them fast ones, with intervals. Lets do hill repeats.
Lets keep warm, lets keep interested. Lets get back home before its dark. Lets keep riding regularly.