No Heat at −30: How Long You Have and When to Leave

In short

At −30 °C (−22 °F) a home with no heat can fall below freezing inside in about a day. Drafty homes go faster.
Babies, older people and anyone ill are in danger long before a healthy adult feels it.
One closed room, layers and sleeping bags buy real time.
Set a temperature at which you leave, and leave while roads and daylight allow.
Hypothermia and frostbite are 911 emergencies.

How fast a house cools

There is no single number, because it depends on insulation, air leaks, wind, sun and size. As a rough guide for −30 °C (−22 °F) outside:

Home	From room temperature to freezing inside
Newer, well-sealed house	One to three days
Average older house	About a day
Drafty house, mobile home or cabin	Well under a day
Apartment with heated units around it	Much slower, often several days

These are estimates to plan with, not promises. Wind makes every row worse. Put a cheap thermometer in the room you live in and write the reading down every few hours. The trend tells you more than the number. See battery room thermometers on Amazon.

Who is at risk first

Babies lose heat quickly and cannot shiver well or tell you.
Older people often do not feel the cold until they are already in trouble.
People who are ill, have heart or circulation problems, or take certain medicines.
Anyone who has been drinking alcohol. It makes you feel warm while you lose heat faster.
Anyone who is wet, hungry or exhausted.

Plan around the most vulnerable person in the home, not the toughest.

Buying time

Move into one small room and close it off. See heat without power.
Insulate the people. Layers, hats, mitts, dry socks, sleeping bags, mats or cushions under you.
Seal the leaks. Towels at door bottoms, blankets or plastic over windows.
Eat and drink. Warm, sweet drinks and regular food keep your body making heat.
Move a little, do not sweat. Damp clothing chills you fast.
Sleep in shifts if the room is very cold, so someone is always watching the others and the CO alarm.

Cold makes people take risks they never would otherwise. Do not bring a barbecue, camp stove, generator or running vehicle into the house or garage for heat. Carbon monoxide kills faster than cold does.

Signs of trouble

Hypothermia: strong shivering, then confusion, slurred speech, fumbling, drowsiness. Shivering that stops in someone who is still cold is a very bad sign. In a baby: bright red, cold skin and very low energy.

Frostbite: skin that is numb, white or greyish-yellow, hard or waxy. Fingers, toes, nose and ears go first.

Both are emergencies. Call 911. Move the person somewhere warmer, take off anything wet, and warm the centre of the body first with blankets and skin-to-skin contact. Do not rub frostbitten skin.

When to leave

Pick your rule now. A reasonable one:

The room you live in is below 10 °C (50 °F) and still falling, or
Anyone vulnerable is in the home and you cannot keep them warm, or
Anyone shows signs of hypothermia, or
Your backup heat or its fuel will run out before the power is expected back.

Then go while it is daylight, the roads are open and the car has fuel. Know two places you could go: family or friends with heat, a public warming centre, a hotel outside the outage area. Take medicines, documents, chargers, pets and warm gear. Shut the water off at the main on the way out. See pipes.

If you cannot leave

If travel is more dangerous than staying, tell someone outside where you are, keep everyone in one room, and call 911 if anyone's condition worsens. Do not wait until it is an emergency to ask for help. Emergency services would far rather move you early.

Sources

Official guidance this page was checked against. If your local authority says something different, follow them.