Wintertime, when it is dark and damp and cold and windy outside, is the quintessential time of year when Germans yearn for Gemütlichkeit and Danish people for hygge. There is no direct translation for either word, but it means cozy-warm-fuzzy-comforting. The term describes a combination of appearance and ambiance, and is culturally linked to the need for physical and psychological protection from the raw fall and winter weather of those countries.
A room, home or restaurant is gemütlich when it is not too big, warm, the lights are dim (maybe candles are lit), the ceiling is not too high, the colors are in the warm spectrum, the sound level is muted or soft music is playing, maybe a fire is lit in the fireplace, you can sink deeply into the soft furniture, the smell of cookies baking in the oven or a thick winter stew simmering on the stovetop might waft through the air, and you feel safe and coddled and know that everything is all right.
You can feel gemütlich by yourself, with a loved one or with a few close friends, but not in a crowd. It feels gemütlich when you sit in front of your fireplace in the late afternoon or evening in comfortable clothes on a soft couch with a cup of tea and a good book and without a care in the world, moreso if the weather is really miserable outside. You cannot feel gemütlich when the sun shines brightly, when the weather is balmy and the windows are open, when you sit in an upright hard chair, when you wear formal clothes, when the place is expansive with high ceilings, or when you are upset and preoccupied.
Now is the time to be gemütlich, because it's over with the Gemütlichkeit as soon as the weather warms and spring fever hits.