Preparing for winter blackouts and heavy snow: heating, carbon monoxide, cars and phone batteries

The short answer

In winter blackouts and heavy snow, the danger is not only the cold but carbon monoxide poisoning. A car exhaust blocked by snow, a generator run indoors, and a fuel-burning heater used without ventilation can all fill a space with this colourless, odourless gas.

When heavy snow is forecast, the first step is to make fewer trips. When the power goes out, use fuel-burning heaters only with ventilation, and unplug electric heaters. Agreeing on these two points at home and at work is the place to start.

When heavy snow is forecast, travel less

When heavy snow is expected, Japan's Ministry of Land, Infrastructure, Transport and Tourism and the Japan Meteorological Agency issue an emergency announcement on heavy snow. The January 2026 announcement asked people in affected areas to avoid non-essential trips, including by working from home, and to allow plenty of time if they must go out. Drivers who have no choice were asked to fit winter tyres, check and carry chains in advance, and carry winter equipment such as a shovel and sand.

The announcement also warned that expressways and parallel national roads may close at the same time, and that public transport may face large, long delays or cancellations. For a small office, a realistic approach is to decide the day before, once the forecast is out: "we work from home tomorrow" or "we move tomorrow's visitor".

If your car gets stuck, clear snow from the exhaust

The Hokuriku Snow Disaster Countermeasure Technology Center, part of the ministry's Hokuriku Regional Bureau, warns that an exhaust buried in snow can cause carbon monoxide poisoning. It advises clearing snow around the exhaust pipe regularly and opening a window slightly for ventilation. It also says to run the heater while watching for running out of fuel or draining the battery, and, when calling for help, to give your location using the national road number and the kilometre posts at the roadside.

Because you can lose your bearings in a blizzard, it advises staying with the car unless you can clearly see a shelter or rescuers, and not stepping out on the traffic side, since other cars may come from behind. Keeping blankets, gloves and other warm items in the car makes it easier to get by with the engine off.

Heating and generators during a blackout

The Consumer Affairs Agency and NITE (the National Institute of Technology and Evaluation) warn never to run a portable generator indoors. Even outdoors, running one inside a car or a tent is as dangerous as indoors or worse; use it in a well-ventilated spot away from doors and windows.

Fuel-burning heaters such as kerosene stoves burn incompletely when there is not enough ventilation, and carbon monoxide rises. NITE advises ventilating often while they are in use, not using them while you sleep, and making sure they are off before bed. It also warns against using gas appliances such as cassette stoves inside a tent or car.

During a blackout, unplug electric heaters and other appliances with built-in heating elements, so they do not switch themselves on and start a fire when the power returns. If you have time before evacuating, also switch off the main breaker. Once power is back, check plugs and cords for damage or scorch marks, switch the breaker on, then plug appliances in one at a time and watch how they behave.

Making your phone battery last

During a blackout, your phone becomes the main way to get information. On iPhone, Low Power Mode dims the screen, sets Auto-Lock to 30 seconds and pauses mail fetch and background app refresh, among other things, to stretch battery life. Turn it on under Settings, then Battery (Power Mode on iPhone 15 and later), or with the battery icon in Control Center. Android phones have power-saving settings too, but names and locations vary by model, so check your maker's guidance.

Habits help as well: do not leave videos or maps open for long, and avoid a household running every phone flat at the same time.

Points to watch

NITE notes that carbon monoxide has no colour, taste or smell; as the concentration rises it causes headaches and, as it progresses, can kill. You cannot smell it, so do not skip ventilation because "it is only for a moment". Before any blackout, open your local power company's outage information and your municipality's disaster alerts once with your family or colleagues, so you know where to look.