Chicago in December: 3°C / 37°F afternoons, −4°C / 25°F nights, and four times November's snow.
Dress for the ground. NOAA's figures for O'Hare put December at 2.6°C by day and −4.2°C at night, but the number that changes your suitcase is snow: 7.6 inches in an average December against 1.8 in November, with NWS Chicago dating the first one-inch fall to around 7 December. NWS Chicago's daily average high slides from 41°F on the 1st to 33°F by the 31st, and the sun sets about 4:20pm all month. None of it keeps the city in. The Christkindlmarket fills Daley Plaza for its 30th anniversary until 24 December, and ZooLights opens in Lincoln Park at 4:30pm, after dark. So pack for standing still on snow: a hooded parka to the knee, two thin layers under it, and boots, gloves and a hat you keep on.
Chicago's December is decided at the ankle and the ear. The snow arrives by the end of the first week, and the city goes out to stand in it anyway.

Knee length is the reason this parka is here. At a Daley Plaza stall at −4.2°C, a hip-length jacket leaves your thighs to the cold, while an insulated charcoal shell covers you from hood to knee and the snap placket over the zip keeps snow out of the teeth. Keep the hood down on the walk and up once the first inch falls, around 7 December.

Pack a fine knit, not a chunky one: it has to go under an insulated parka without binding at the shoulder. This charcoal-black crew is what shows at the neck when the parka is zipped, and it is the whole top half of the outfit once the coat comes off in your seat at the Lyric Opera House for the Joffrey's Nutcracker, 4 to 27 December.

An hour at the Christkindlmarket and then dinner indoors is the December pattern, and merino handles both ends of it. It holds heat while you stand still on the plaza, and it does not turn clammy when you walk into a heated room. Sage is the one soft colour under all that charcoal, and it shows whenever the knit comes off.

Corduroy, not denim. Fine-wale pile traps a layer of air that flat cotton twill does not, which matters on the ZooLights paths from 4:30pm as the evening heads for −4.2°C. Straight leg so the hem falls over the shearling cuff of the boot instead of bunching inside it, and charcoal so road-salt spray from the treated pavements does not show.

Snow decides this slot. An average December at O'Hare brings 7.6 inches of it, so from the second week you meet slush at every crossing in the Loop. Oiled brown leather keeps it out, a deep lug grips packed snow on the plaza, and the cream shearling cuff closes the ankle, where snow gets in over the top of a shorter boot.

Keep them on. Black leather with a cashmere lining sheds snow that soaks straight into a knitted glove, and the short knit cuff tucks under the parka sleeve so no wrist shows while you work along the stalls. They are thin enough to handle a card at the Christkindlmarket and go straight back on for the walk out into a −4.2°C evening.

Lincoln Park Zoo is blunt about ZooLights: "Unless otherwise posted, ZooLights will take place in rain, snow, or shine. Please dress accordingly!" A chunky cranberry rib with a deep fold-up cuff puts two layers of wool over your ears, so the parka hood can stay down and out of your view of the lights. Cranberry is also the only strong colour in the capsule.

Zip it shut. An open tote on a snowy plaza fills with whatever is falling, and a zip top keeps the gloves, a card and a spare pair of socks dry between Daley Plaza and dinner. Two top handles go over the parka shoulder with no long strap to slide off, and cognac is the warm brown that keeps all that charcoal from going flat.
Sage merino base under the charcoal fine knit · charcoal corduroy trousers · brown leather snow boots · parka open, hood down · cognac tote. The Riverwalk and the Loop on foot from ten, lunch indoors at one, and every outdoor plan done before the sun sets at about 4:20pm.
Same base and knit · corduroy · boots · parka zipped, hood down · black leather gloves on · cranberry beanie · cognac tote. The Christkindlmarket on Daley Plaza after dark, open until 8pm Sunday to Thursday and 9pm on Fridays and Saturdays, with the evening heading for −4.2°C.
A suggested look — charcoal hooded parka, charcoal fine-knit crew, charcoal corduroy trousers, brown leather winter boots, black leather gloves.
Cold, dark early and increasingly white. NOAA's figures for Chicago O'Hare give an average December high of 36.6°F (2.6°C) and a low of −4.2°C, with 2.11 inches of precipitation across 10.6 days, 4.8 of them above a tenth of an inch. Snowfall averages 7.6 inches, against 1.8 in November. The month cools as it goes: NWS Chicago's daily average high is 41°F on 1 December and 33°F on the 31st. Daylight holds near 9 hours 10 minutes, and the sun sets close to 4:20pm every day.
A charcoal knee-length insulated parka with a hood, a sage merino long-sleeve base, a charcoal-black fine-knit crew, charcoal fine-wale corduroy trousers, brown leather waterproof snow boots with a shearling cuff and a deep lug, black lined leather gloves, a cranberry ribbed wool beanie and a cognac zip-top tote. That covers a −4.2°C evening at the Christkindlmarket, a snowy ZooLights walk and a heated restaurant afterwards. Leave October's wool overcoat, suede boots and knitted gloves at home; by the second week the snow finds all three.
Dress to stand still outdoors after dark. The Christkindlmarket runs on Daley Plaza, 50 W Washington St, from 20 November to 24 December 2026, opening at 11am daily and closing at 8pm Sunday to Thursday and 9pm on Fridays and Saturdays, with a 4pm close on Thanksgiving and Christmas Eve. This is its 30th anniversary: it began on Pioneer Court in 1996, modelled on Nuremberg's Christkindlesmarkt, and moved to Daley Plaza in 1997. Wear the parka zipped, merino and a fine knit under it, lug-soled boots, gloves you keep on and a beanie.
Early, unless snow is the point. NWS Chicago's daily averages run from 41°F and 28°F on 1 December to 33°F and 21°F on the 31st, and the first one-inch snowfall lands around 7 December. The calendar favours the first three weeks: the Christkindlmarket closes on 24 December, ZooLights shuts on the 24th and 25th, and the Joffrey's Nutcracker runs 4 to 27 December. Late December is colder, with better odds of snow on the ground. NWS Chicago gives a White Christmas a 34% chance and defines it: "A 'White Christmas' is defined as one having at least 1 inch of snow on the ground."
December runs about six degrees Celsius colder by day and five at night, and brings four times the snow. Our November page works from 9°C / 48°F afternoons and 1°C / 34°F nights with 1.8 inches of snow; NOAA's O'Hare figures put December at 3°C / 37°F and −4°C / 25°F with 7.6 inches. Precipitation days barely move, about 10 against 11, but far more of December's falls as snow. That is why November's belted wool coat and lined ankle boots give way here to a hooded parka, snow boots and a hat.
Dark outerwear, a hat pulled over the ears, and leather on the feet that has met road salt before. The city has a long claim to that last part. Florsheim was launched in 1892 in a small factory in Chicago by Sigmund Florsheim and his son Milton, and Horween Leather has been tanning in Chicago since 1905, best known for its shell cordovan and Chromexcel boot leathers. The local December uniform is a long parka or down coat in black, charcoal or navy, gloves worn rather than pocketed, and one colour at the head.