Extreme cold wave threatens US and Canada with polar vortex collapse in March

An impending climate event of significant magnitude is set to reshape North America’s weather in mid-March, as forecasts predict a second polar vortex collapse in 2025, unleashing freezing temperatures, intense blizzards, and biting winds across the United States and Canada. Meteorologists warn that this phenomenon, following a disruptive episode in February, could be unusually severe, even as winter begins to wane. The earlier collapse affected over 150 million people with record lows and heavy snow, and this upcoming event, driven by a Sudden Stratospheric Warming (SSW), is expected to break the polar jet stream’s barrier, releasing Arctic air masses southward. This shift could impact millions, straining infrastructure and disrupting daily life in regions unaccustomed to such late-season extremes.

The polar vortex, a swirling mass of cold, low-pressure air encircling the Arctic at about 30 kilometers above the Earth, plays a vital role in regulating winter weather in the Northern Hemisphere. When stable, it traps frigid air near the poles, but its collapse, anticipated for March, destabilizes this system, allowing icy air to spill into mid-latitudes. In the US, cities like Chicago and Minneapolis brace for lows dipping to -30°C, while in Canada, Toronto and Winnipeg face projections nearing -40°C. This event not only tests the resilience of local populations but also sparks discussions about the increasing frequency of vortex disruptions, potentially tied to global climate shifts.

The intensity of this forecast has already spurred action among authorities and residents preparing for the expected fallout. February’s collapse, which paralyzed transportation and strained power grids, serves as a stark reminder of what’s at stake, with predictions suggesting the March event could surpass its predecessor in scope and disruption during a transitional season.

Understanding the polar vortex and its triggers

The polar vortex is a vast atmospheric structure of cold air and low pressure that intensifies around the poles from November to March in the Northern Hemisphere. Located in the stratosphere, its winds, exceeding 250 km/h, create a natural barrier that confines Arctic air to polar regions. When undisturbed, the polar jet stream—a high-altitude wind current—flows steadily, ensuring predictable weather in mid-latitudes like the US and southern Canada.

Disruptions, however, can upend this balance. The Sudden Stratospheric Warming, a key trigger for the collapse, occurs when stratospheric temperatures spike by up to 50°C in days, throwing the vortex’s winds into disarray. Normally blowing west to east, these winds may weaken or reverse, causing the jet stream to wobble and allowing Arctic air to surge south. This results in extreme cold snaps and erratic weather patterns across broad regions.

In 2025, two such events within months—February and now March—raise questions about broader climate influences, such as Arctic warming, which may be weakening the vortex’s stability over recent decades.

Expected impacts of the March collapse in North America

Forecasts for the mid-March polar vortex collapse signal major challenges for the US and Canada. In the US, the Midwest and Northeast, still reeling from February’s ordeal, anticipate temperature drops of up to 15°C below seasonal averages. Chicago could see lows of -34°C, while New York might hit -20°C, rivaling the harshest winter days in recent memory.

In Canada, provinces like Ontario and Manitoba expect even graver conditions, with Toronto potentially dropping to -25°C and Winnipeg nearing -42°C. The mix of extreme cold, blizzards, and strong winds threatens transportation, with likely road closures and flight cancellations, alongside surging energy demands that could strain power grids already tested earlier this year.

Coastal areas, such as the US East Coast, may face heavy precipitation, including freezing rain and snow buildup, as Arctic air clashes with Atlantic moisture systems. The prolonged impact, possibly lasting up to two weeks, will challenge urban and rural communities alike in a month typically linked to spring’s onset.

Timeline of polar vortex events in 2025

The year 2025 has already marked itself with two major polar vortex collapses in under two months. Here’s a timeline of the events:

• February: First collapse releases Arctic air, hitting central and eastern US with record lows and heavy snow.
• March: Second collapse projected for mid-month, with greater intensity and reach across the US and Canada.
• Ongoing monitoring: Scientists track potential for additional events before winter ends.

February’s episode brought extreme cold to over 150 million people, with Boston accumulating up to 30 cm of snow and Detroit facing traffic shutdowns. The March event, though occurring in a transitional period, could exceed these impacts, underscoring 2025’s volatile weather patterns.

Preparations to face the extreme cold

With the March collapse looming, authorities across the US and Canada are ramping up preparations. In the US Midwest, cities like Minneapolis are stockpiling road salt and inspecting heating systems in public buildings. In the Northeast, New York and Boston deploy emergency crews to handle potential power outages, a recurring issue in extreme weather events.

In Canada, Ontario and Quebec expand shelter capacities to protect vulnerable populations, while Manitoba issues hypothermia warnings for rural areas. Residents are also gearing up, with spikes in demand for portable heaters and insulation materials in cities like Toronto and Chicago, where February’s cold snap offered a harsh lesson.

Local weather services issue frequent alerts, urging people to avoid unnecessary travel and stockpile emergency supplies like food and blankets amid risks of prolonged disruptions.

Key facts about the polar vortex and its effects

The polar vortex collapse is not a new phenomenon, but its rising frequency draws scrutiny. Notable facts include:

• Location: Stratosphere, about 30 km above Earth.
• Wind speeds: Can exceed 250 km/h when stable.
• Average impact: Temperature drops of 10°C to 15°C below norms.
• 2025 events: Two collapses by March, a decade high.

Research since 2010 suggests these incidents are becoming more common, possibly due to Arctic warming, which narrows the temperature gap between the pole and mid-latitudes, weakening the vortex.

Emergency measures to counter climate impacts

Local governments in the US and Canada are implementing strategies to mitigate the collapse’s effects. Chicago bolsters power line maintenance, while Toronto plans enhanced public transit for cold conditions. Both nations prioritize protecting the homeless, opening heated shelters to reduce risks.

February’s chaos, with over 2,300 US flight cancellations due to extreme weather, informs current efforts. Airports like Minneapolis-Saint Paul enhance de-icing operations, and Manitoba’s highways undergo preemptive checks to avoid snow blockages.

Lessons from February’s collapse for March

February’s event left critical lessons for North America. In the US Midwest, blackouts impacted 190,000 people, while Alberta, Canada, saw blizzards isolate rural communities. These incidents exposed the need for stronger power grids and weather-ready transportation systems.

Facing March’s forecast, preparations are more robust. Schools in Michigan consider suspending in-person classes, and Ontario businesses adapt operations to safeguard workers. The swift response reflects adaptation to an unusually turbulent 2025 winter.