As the weather cools, craft brewers trade crisp, light warm-weather styles for the boozier, spiced and malty beers of autumn. The popularity of wet hops, pumpkin-spice everything and Oktoberfest brews has made fall the season en vogue for limited-release brews.

Brown Shugga, a hop-heavy strong ale by Petaluma’s Lagunitas. BigLeaf Maple Autumn Red by San Francisco’s Anchor Brewing. Ale of the Hermit and bourbon barrel-aged Ryetopia by San Jose’s Hermitage Brewing Company. Winter Camp ale by Strike, another San Jose craft brewer. Pumpkin Sour—a tart, tangy twist on conventional fall flavors—brewed in San Jose by the farm-to-table artisans of Almanac.

“Think of it as our ‘anti-pumpkin’ pumpkin beer,” Almanac brewmaster Jesse Friedman explains. “A pumpkin that evokes the fall flavors without any of the cliches attached to the usual squash seasonals.”

San Jose’s big-daddy brewer, Gordon Biersch, announced this week that it’s bringing back a seasonal favorite. The classic dark and full-bodied WinterBock ($8.99 to $9.99 per six-pack, 7.5 percent ABV) will sell through January, when the novelty of late-year seasonal brews wears off anyway.

True to Gordon Biersch tradition, WinterBock adheres to a German purity law called Reinheitsgebot. The decree, which dates back to 1516, limits the recipe to four ingredients—water, hops, yeast and malt.

Though made up of just four basic ingredients, WinterBock blends five types of malts: Munich, pilsner, black and two variations of caramel. Mahogany hued with a bready aroma, it pours out a creamy, light tan head.

Hungry monks in 11th century Bavaria invented bock to curb their hunger during fasts. By brewing it thick, caloric and nutrient-dense, they could circumvent the agony of abstaining from food during Lent and other religious observances. The result, of course, is that bocks have become associated with the holidays and are heavier than most brews.

Gordon Biersch founder Dan Gordon calls the monastic meal replacement one of the greatest loopholes of all time, a clever, if not slightly heretical, workaround of church-imposed piety.

“We take pride in continuing the ‘meal in a glass’ tradition that monastery breweries began 10 centuries ago when they figured out that a strong, dark beer would fulfill their bread and water diet,” said Gordon, a San Jose native who studied brewing in Germany. “It’s easy to see how fasting on a 7.5 percent ABV beer would take your mind off the hunger pangs.”