Are you doing a brew a month? Regardless, you have to brew ahead of the seasons a bit. (Of course, you don't have to drink seasonally...but i like to)
You could still sneak in a winter brew or two right now, maybe not a spiced Christmas ale, but a fairly hefty stout. Do you lager? Think a good-sized bock now to drink in March. Porter-Brown-Amber-Pale Ale/Bitter as you move into the warmer months.
Witbier or Hefe for May/June would be a must for me...maybe a blond for the hot weather. Spritzy Belgian Blonde would be nice. A saison can actually be brewed during the hot weather (something you really need to prepare for.)
For fall, darker lagers, oktoberfest, pumpkin brew.
If you want to do something big...barleywine, Belgian Quad, Impy Stout...plan way ahead to drink next winter.
Think about re-using yeast. Maybe Spring's Belgian blond yeast is re-used for a big Belgian that is stored for many months. Witbier yeast for Grand Cru. ESB followed by English IPA. Etc.
FYI, I've never had a long term plan that I didn't change. It's fun to plan...and to re-plan, and re-plan...