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Live forecasts update automatically; written guidance last reviewed 16 June 2026 by the Toronto Post Weather Desk. Data from Environment and Climate Change Canada and other national met services via Open-Meteo.
A polar vortex collapse brings a 15 °C to 20 °C temperature drop below seasonal norms across central and eastern Canada, with Toronto wind chill values near –30 °C by late this week. The event results from a sudden stratospheric warming that displaces the polar vortex southward.
What happens when the polar vortex collapses?
The polar vortex is a large area of low pressure and cold air that normally spins over the Arctic. When it weakens, a process often tied to a polar vortex collapse 2026 pattern, the cold air spills south into the mid‑latitudes. What causes the polar vortex to weaken is a rapid warming of the stratosphere, which disrupts the vortex’s circulation. This sends Arctic air across the Prairies, Ontario, and Quebec, bringing the kind of sharp temperature plunge expected later this week.
Polar vortex collapse weather forecast for Canada?
For Toronto, daytime highs will struggle near –15 °C with overnight lows near –25 °C, well below the seasonal average of –1 °C. Wind chill values of –30 °C to –35 °C are possible, creating frostbite risk in minutes. A live polar vortex map live from Environment and Climate Change Canada shows the cold air centred over Hudson Bay, sliding southeast. Some regions in Saskatchewan and Manitoba could see 48‑hour temperature drops of 25 °C. This polar vortex collapse weather event is expected to persist for 5–7 days before the vortex re‑establishes. For ongoing Canada Weather Warnings and Severe Weather updates, check the Toronto Post hub.
What is a polar vortex collapse?
A polar vortex collapse occurs when the Arctic’s normally stable cold‑air circulation weakens and splits or shifts south. This allows frigid polar air to spill into Canada and the northern United States, causing extreme cold spells.
How long does a polar vortex collapse last?
Typically 5 to 10 days. The cold air may linger longer if the vortex remains displaced. The current event, forecast for polar vortex 2026, is expected to persist about one week before the vortex recovers.
Is a polar vortex collapse linked to climate change?
Research suggests that Arctic amplification—warming at the poles—can weaken the polar vortex more frequently, making collapses more common. While an individual event is weather, the trend lines point toward a shift in polar vortex meaning and behaviour.