How to Help Outdoor Cats in Winter

Pack the shelter with straw, not blankets — blankets absorb moisture and freeze against the cat. Keep the shelter small, because it is heated by the cat’s own body. Give it two exits. Then solve water, which is the harder half: a 12 W thermostatic heated bowl runs about $6.34 for a whole winter at the ceiling, and nothing else reliably works.

The mistake almost everyone makes

People put blankets, old towels, fleece and cushions into outdoor shelters, because that is what warmth looks like indoors. Outdoors it is actively harmful, and the mechanism is moisture rather than temperature.

Fabric absorbs water — from rain tracked in on fur, from snow, and from the cat’s own breath and body over a long night. Once damp, it holds that water against the animal and conducts heat away far faster than dry air does. In a hard freeze it stiffens. A cat sleeping on a damp blanket at 20 F is colder than the same cat on a bare insulated floor.

Straw behaves the opposite way. The stems are hollow, so it traps a lot of still air; it sheds water rather than soaking it up; and a cat can burrow into it, which puts insulation underneath and around the animal instead of just under it. Not hay — hay is dried grass, it absorbs water and it molds.

Why smaller is warmer

Shelter and station, on published figures

Setting the shelter up

1. Raise it off the ground. Two bricks or a pallet. Ground contact wicks heat out and lets meltwater in.
2. Two openings, one sheltered. A single door is a trap. Face the main opening away from prevailing wind, and keep both small — a cat-sized hole loses less heat than a generous one.
3. Pack it with straw, generously. Not a layer on the floor — enough that the cat has to burrow. Top it up when it flattens or gets damp.
4. Put it somewhere quiet and against something. A wall, a fence, under a deck. Shelter from wind matters as much as the box itself.
5. Do not block the entrance to keep heat in. A flap or a curtain is fine; anything a cat has to fight is a shelter it stops using.
6. Check it without disturbing it. Community cats abandon shelters that smell of frequent human handling. Top up straw and water and leave.

Water is the harder problem

A shelter works unattended all winter. Water does not: a bowl put out in the morning is ice by lunchtime, and the tricks people try — deeper bowls, warm water, a ping-pong ball on the surface, a dark bowl in the sun — buy minutes to an hour. In a real freeze the only thing that works is a thermostatic heated bowl, and the good news is that it is cheap: about $6.34 of electricity for a whole 120-day winter on a 12 W unit at the published ceiling, and nearer half that in practice.

The constraint is not cost but the cord. Both makers state the unit should not be used with an extension cord, and the K&H cord is 5.5 feet. Plan the outlet — ideally a GFCI outlet — before you plan the station. Our heated water bowls page works through the three live options and what each maker will and will not publish.

The kit, and who each piece is for

The PETSFIT insulated outdoor house is the pick where there is no power, which is most places. Foam panels on all walls and the roof, a published interior of 22 by 17 by 15 inches, a main door with a PVC curtain and a separate escape door — so it meets the two-exit rule out of the box rather than needing modification. For: gardens, yards and alleys with no outlet; one or two regular cats. Skip it if: you have several cats and only one shelter — buy two small ones rather than one large one, because volume is the enemy.

The K&H Thermo-Kitty Cafe is the pick if you have power and you are feeding as well as watering. Two 302 stainless bowls, 24 oz and 12 oz, thermostatic for both food and water, MET listed, one plug. Stainless matters outdoors: it wipes clean and does not hold odor the way plastic does. For: established community cat feeding stations near an outlet. Skip it if: you want to know the running cost — K&H publishes no wattage and no dimensions for this unit, so it is the one thing here we cannot cost.

The K&H Thermal-Bowl is the pick if water is all you need, and it is the cheapest heated thing to run here at a published 12 W on the small variant. MET listed for outdoor use, 5.5 ft wrapped chew-resistant cord, four sizes with inside dimensions published for three of them so you can match it to a porch or a shelter entrance. For: one or two cats, a porch or garage with an outlet. Skip it if: you are watering a colony — size up, and expect to refill it daily regardless of the heater.

What this does and does not solve

• Shelter and water are not veterinary care. A thin, limping, injured or visibly sick cat needs more than straw. The Cornell Feline Health Center is the place to start reading, and a local TNR or rescue group is the place to call.
• Feeding outdoor cats is a commitment, not a gesture. Cats come to rely on a station. Starting one in November and stopping in January is worse than never starting.
• Check with neighbors and local rules. Feeding stations and shelters sit in other people’s sight lines, and in some places there are ordinances about it.
• Check under the car. Cats sleep against warm engines and in wheel arches. Bang the hood before you start the engine in winter.

The rest of the setup

Our outdoor cat houses page ranks the shelters on published insulation and interior volume, and heated water bowls covers the water half in full. For the cats already indoors, keeping cats warm in winter is the cheaper and easier problem.