Even better news: You can now buy seasonal craft beer just about anywhere, including your local grocery store. There are also specialty beverage stores like
Binny's Beverage Depot that usually carry a good variety of interesting seasonals. If you can't find a decent selection locally, consider a "Beer of the Month" club like MicroBeerClub.com or The Connoisseur's Beer Club, where a selection of some of the finest craft brews available lands on your doorstep each month. (Check first to see if your state allows shipment of alcoholic beverages.)

Here are The Beer Sommelier's recommendations for the best brews for each season:

Autumn
Perhaps related to harvest time in many parts of the world, autumn tends to feature the widest variety of seasonal styles.
Try: Southern Tier's Pumking (New York) "rich and buttery pumpkin pie in a glass," and the classic Ayinger Oktoberfest (Germany).
Goes well with: Most spiced beers are meant to be savored on their own, but Oktoberfest lagers are lighter and pair more easily with everything from mild cheeses to poultry, or traditional German fare.

Winter
Winter is the time for what Simpson calls "big beers" like Imperial stouts and winter ales, which tend to fall at the far end of the style scale. "They're big in alcohol, big in body, flavor, palate sensation and often big in bitterness, but hopefully still balanced," he says.
Try: barrel-aged versions like Goose Island's Bourbon County Stout (Illinois), Alemith's Speedway Stout (California), or a Belgian like Delirium Noel.
Goes well with: Either alone or with fatty, smoked meats.