|You say it's January and I'm dressed for summer?|
Many styles of beer have a seasonal connotation: pumpkin beer in the fall, light hoppy beers and saisons in the summer, dark and heavy beers during the winter. Whether it be due to procrastination, or the restrictions of ambient temperatures, I frequently find myself drinking beers out of season. In fact, I think I almost prefer it. Sure, during winter I enjoy a good barley wine or an imperial stout on occasion, but more often, when it's dark for 16 hours a day and below zero, a nice, hoppy IPA really helps lighten things up. Likewise in summer, a low-gravity, jet-black stout might seem out of place, but it's probably my preferred summer quencher.
There are also practical considerations. Some of us are lazy and brew our Oktoberfests in October, or more frequently in my case, brew saisons at the peak of the summer heat. Since I don't use a temperature controller or electric refrigeration (ice packs all all the way, baby!) it's almost a yearly tradition to wait until August to brew a saison when those stubborn saison yeasts can be happy and attenuative at 80 degrees. And it's not until December that I'm usually thinking about brewing something like an imperial stout. The vigorous fermentation from those high gravity beers can easily generate excessive heat during summer when temperatures are already high. That being the case, I usually pop my first bottle of "summer" saison in September, and that winter-brewed imperial stout is ready for tasting in June.
I do enjoy planning ahead and brewing my Christmas beers in the summer, and brewing IPAs and Hefeweizens in the winter, but that's not always possible. Plus, variety is one of the biggest reasons to homebrew in my mind, so having commercial saisons in the summer when they're available is just fine. I'll drink mine in the fall and winter while the commercial brewers are releasing their winter ales and imperial warmers etc. If you're going to brew your own beer, why not make your own calender too?