What an Extreme Cold Warning Means, and How to Prepare

An Extreme Cold Warning tells you that dangerously low air temperatures or wind chill values are expected or occurring in your area, and that people and infrastructure are at risk if precautions are not taken. Since October 1, 2024, the U.S. National Weather Service has used the term Extreme Cold Warning to replace wind chill warnings, while Environment and Climate Change Canada has used extreme cold warnings for several years, with regional thresholds set to local climate norms.

What the warning actually means

An Extreme Cold Warning is not a weather curiosity, it is a public-safety product designed to trigger action, and it generally means one of two things: the air temperature itself will be dangerously low, or the combined effect of temperature and wind will create a wind chill that is hazardous. Criteria vary by agency, and by local forecast office, but the intent is consistent, protect life and critical services.

How thresholds differ, plain language

• United States (NWS): Extreme Cold Warnings are issued when dangerously cold air temperatures, or wind chill values at or below about -20°F, are expected or occurring, with Cold Weather Advisories covering the milder range roughly between -10°F and -20°F, depending on local office criteria.
• Canada (ECCC): Warnings are issued using temperature or wind chill criteria adjusted for local climate, with threshold values ranging roughly from -30°C to -55°C in the Arctic and far north. Coastal and southern thresholds are set lower, to reflect local risk.

These numbers are useful anchors, but the local forecast office decides the precise thresholds for your county, territory, or province, because what counts as extreme changes with local norms, housing stock, and population vulnerability.

Why the naming change matters

Meteorologists and emergency managers moved away from the phrase wind chill in warning titles so the public understands that extreme cold can be dangerous even when wind is light. Cold that follows a storm, or long, clear nights with radiative cooling, can freeze pipes, strain electrical systems, and cause hypothermia or frostbite even without high winds. Simplifying product names, the agencies say, reduces confusion and encourages protective action.

Cold is dangerous, wind or no wind, and the warning is intended to make that unmistakable.

Health risks, who is most at risk

Exposure to extreme cold can rapidly lead to frostbite and hypothermia, two medical conditions that are preventable with timely action:

• Frostbite damages skin and deeper tissue, often affecting fingers, toes, nose, cheeks and ears, and can occur within minutes at very low wind chill values.
• Hypothermia is a drop in core body temperature, and becomes a medical emergency when the core temperature falls below 95°F (35°C).

People at elevated risk include older adults, young children, people with chronic illnesses, outdoor workers, people who use alcohol or certain medications, unsheltered individuals, and anyone with inadequate heating or insulation in the home.

Preparing and responding, practical steps

For households

• Check and maintain heating systems, and keep at least one working carbon monoxide detector when using alternative heat sources.
• Insulate pipes, let faucets drip when very cold weather is expected, and know how to shut off a frozen pipe if it bursts.
• Create a simple winter kit: blankets, flashlight, extra batteries, nonperishable food, a battery-powered radio, and a full mobile phone power bank.
• Limit travel during warnings, and if you must drive, keep warm clothing, blankets, water, and a charged phone in the car.

For employers and outdoor workers

• Schedule work-rest cycles, provide sheltered warming areas, require layered clothing and water-resistant outerwear, and use a buddy system so coworkers watch for early signs of hypothermia or cold stress.
• Consider delaying nonessential outdoor work during the coldest hours, and ensure training on cold-related illnesses.

For communities and emergency managers

• Open warming centers proactively, check on people living alone and older adults, and plan for power outages and increased demand on medical services.
• Coordinate with utilities to identify vulnerable neighborhoods with aging infrastructure and prioritize response.

Infrastructure impacts to watch

Extreme cold can strain energy grids, because heating demand rises sharply at the same time power generation and distribution can be stressed by frozen equipment. Piped natural gas and water can freeze, and road and transit systems often face cascading outages that impede emergency response.

• Power: Prolonged cold increases demand and the risk of outages. Backup power plans, triage for critical facilities like hospitals, and safe generator practices are essential.
• Water: Frozen pipes can burst when they thaw. Simple measures, such as insulating exposed pipes and keeping interior temperatures steady, lower the risk.
• Transport: Icy roads and visibility issues raise crash risk, while cold affects vehicle batteries and diesel fuel can gel in extreme low temperatures.

Forecasting, wind chill, and the numbers

Meteorologists use both air temperature and wind speed to calculate wind chill, which estimates how cold exposed skin actually feels. The standard wind chill formula used for temperatures in degrees Fahrenheit and wind in miles per hour is:

```
Wind Chill (°F) = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16)
```

Where T is air temperature in °F, and V is wind speed in mph. The wind chill value is an index for exposed skin, not a measure of heat loss for a bundled person indoors.

The climate context, two scientific viewpoints

Some researchers have linked Arctic warming and changing sea ice patterns to a higher frequency of particular polar vortex disruptions, which can allow very cold Arctic air to spill into the mid-latitudes. Other studies find no detectable trend in cold extremes over recent decades, and the question remains an active area of research.

Presenting both perspectives helps readers understand that extreme cold events can occur in a warming world, and that the drivers of individual cold outbreaks are complex, involving the interplay of stratospheric dynamics, ocean conditions, and regional weather patterns.

Quick reference table: typical product meanings

What to do if you see an Extreme Cold Warning for your area

• Stay inside if you can, and bring pets indoors.
• Check on neighbors who may be vulnerable, and verify that heating systems are working.
• Avoid using gas ovens or grills to heat indoor spaces, to prevent carbon monoxide poisoning.
• If you must travel, tell someone your route, carry a winter survival kit, and avoid traveling alone.

The simplest actions—dress warmly, limit time outdoors, check on neighbors—save lives during extreme cold.

Where to get reliable alerts and more information

• Your local National Weather Service office or national meteorological service for official warnings and local criteria.
• National and local public health agencies for hypothermia and frostbite guidance.
• Emergency management offices and community organizations for warming centers and shelter information.
• Trusted nonprofit sources such as the American Red Cross for preparedness checklists.

Extreme Cold Warnings are blunt tools, but they are blunt for a reason, they are issued when conditions become a direct threat to life and infrastructure. Knowing what the warning means for your community, and taking a few straightforward steps before the worst of the cold arrives, reduces risk for families, neighbors and the workers who keep essential services running.