What’s in a beer garden? Is it defined by communal picnic bench tables in an open-air space? Does it need to serve lagers in steins and weizen glasses and soft pretzels with mustard?

Can it have a roof?

Maybe. In the Bay Area, we like drinking outside as much as possible. But weather patterns of San Francisco and its surrounding cities — fog, rain and rapid weather changes — are also part of everyday life. Where's a beer fan to go when the clouds roll in?

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Lots of places, actually.

Breweries and bars in San Francisco, Oakland and other nearby cities have embraced the all-weather appeal of indoor beer gardens.

Notable among them is Willkommen, opened by San Francisco brewery Black Hammer. In May, the brewery opened its sunlit corner space in the Duboce Triangle, inspired by co-founder Jim Furman's trip to Germany.

As Black Hammer told SFGATE at the time, "[Furman] really wanted to recreate that feeling like you're walking into Oktoberfest or enjoying some of the outdoor environments where people are drinking and it's lively and you're seeing large groups of people celebrating."

Barebottle co-founder Lester Young can relate. An indoor beer garden appealed to him and his team because he had also seen how in other countries, such spaces are hubs for not just drinking, but for community socializing.

"You hear a lot about biergartens [in Germany], but until you go to one, you don’t understand it," he says. "There's big integration of beer in culture and family life. Beer, we think of as a vice. A dark bar, adults-only thing [in the U.S.]. You see how beer is received in other countries, it's an integral part of family life. You take your children, watch the dogs chase each other around. That didn’t exist here."

The indoor beer garden model, however, goes beyond San Francisco. Other breweries, like Fieldwork, were early local adopters of the taproom set up, as were bars like Lost & Found. See some of our favorites in the above gallery.

Alyssa Pereira is an SFGate digital editor. Email: alyssa.pereira@sfgate.com | Twitter: @alyspereira