Every November for the last 25 years, a lively crowd of regulars has packed Simon’s Tavern in Andersonville for a can’t-miss holiday tradition. The Prohibition-era speakeasy, operating legally since 1934, is an institution in Chicago, known for its live music and kitschy Swedish decor. But on one special night — this year on Thanksgiving Eve — they gather to kick off the official start of glögg season.

Scott Martin, the tavern’s owner, serves as master of the ceremony, pouring steaming pots of house-made glögg into five-gallon dispensers for the waiting throng. As the tavern fills with the smell of red wine and cinnamon, orange peels and cardamom, he’ll call out from behind the bar, “What time is it?” That’s the cue for his patrons to roar back in unison, “It’s glögg time!” And just like that, the holidays have officially begun. Glögg, or gløgg, if you’re Norwegian, is just one of many variations of mulled wine savored throughout the chilliest corners of the world.

The French enjoy their vin chaud, the British their wassail. In Germany and Austria — and at Chicago’s Christkindlmarket too — it’s known as glühwein. Usually, mulled wine is made from red wine, although sometimes white, sweetened and simmered with citrus peels and a medley of warming spices.

Whatever alcohol is evaporated while cooking is often replaced with a shot of liquor, typically aquavit, vodka, brandy or rum. Served steaming hot, “it’s just Christmas in a mug.