Do chickens need a heat lamp in winter?

Short answer: your adults almost certainly don't. Your brooder does. Here's the difference and the math for both.

The frostbite myth

Frostbite on combs isn't a cold problem — it's a moisture problem. A dry bird at -10°F stays fine; a damp bird at +25°F loses comb tips. That's why the answer to winter is never "seal it up and add heat." Sealing traps the water vapor from six birds' breath and droppings, the bedding goes damp, and ammonia plus moisture does its work. Heat lamps add risk — they cause more coop fires each year than cold kills chickens — and the power goes out exactly on the coldest night, shock-freezing heat-dependent birds.

Ventilation: the number that matters

Rules: vents above roost height, out of the wind side, predator-screened with ½" hardware cloth. If you see condensation on the windows in the morning, add vent area — the coop is telling you it's too wet. Deep-litter bedding (pine shavings, turned weekly) manages humidity from below; vents handle it from above.

When adults DO need heat

Three real cases: sustained lows below -20°F (supplement 250 W red bulb per 16 sq ft on a thermostat), a heat-dependent breed you bought as adults (frizzles, some silkies), or birds recovering from illness. If you heat, do it safely: thermostat control, bulb secured with chain (clamps fail), 18"+ clearance from bedding, rated cords, and a bulb cage. The goal is taking the edge off, not a 60°F coop — a 30–40°F dry coop is a healthy one.

Brooder math (this is where lamps are required)

Chicks can't thermoregulate for weeks. Targets: 95°F week one, minus 5°F per week, feathered out around week six. A 250 W red bulb covers a 4×4 ft brooder; a 100 W bulb covers a small 2×2 ft brooder in a warm house. Watch the chicks: panting at the edges = too hot; tight huddle with loud peeping = too cold. Raise the lamp or lower the wattage rather than trusting the dial.