Were regional climate patterns responsible for September 2025 warmth?

Yes, regional climate patterns were directly responsible for the exceptional warmth in Calgary during September 2025. The primary driver was a strong, persistent ridge of high pressure—often called an "Omega block"—which established itself over western Canada. This ridge led to a dramatic northward bulge in the jet stream, cutting off the flow of cooler, wetter weather systems and trapping hot, dry air over Alberta and much of the Prairies.news.yahoo+2

This atmospheric blocking pattern created a prolonged period of above-normal temperatures, with some regions experiencing temperatures 10–15°C above typical September values. Similar climate anomalies were reported province-wide, leading not only to warmth but also to the extreme drought conditions observed.news.yahoo+2

Atmospheric forecasts anticipated these patterns several months in advance, with environment agencies expecting both above-normal temperatures and below-normal precipitation for much of Alberta through September 2025. There was no significant El Niño or La Niña at play during this time, so the blocking high was a dominant regional force, not a global climate oscillation effect.open.alberta+1

In summary, the record warmth was caused by a lasting ridge of high pressure (blocking pattern) and a distorted jet stream, driving local atmospheric conditions that favored persistent heat.producer+2

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