Causes of drizzly cool summer on Canadian prairies in 2025

The primary causes of a drizzly, cool summer on the Canadian Prairies in 2025 appear to be tied to persistent and unusual weather patterns, particularly the interaction between cooler Pacific air, looping disturbances, and the position of large-scale systems such as ridges and troughs.

Key contributing factors include:

• Active weather pattern with frequent disturbances: A building ridge to the south and a trough to the northeast have resulted in a steady stream of disturbances moving across the Prairies, producing regular showers but only moderate rainfall. The pattern supports almost daily precipitation in some areas, primarily from cooler, Pacific-sourced systems rather than moisture-laden air from the southern U.S. These showers are often scattered and associated with cooler-than-average air^[1].
• Cool Pacific air: Instead of drawing warm, humid air from the U.S. Plains, many weather systems on the Prairies in 2025 have brought cooler and somewhat moisture-laden air from the Pacific, supporting more persistent cloud cover and light rains typical of "drizzly" conditions^[1].
• Pattern reversals and spring-like conditions into summer: There was a notable pattern reversal in June, with widespread cooler-than-normal temperatures from southern B.C. across the Prairies. This return to spring-like conditions featured single-digit daytime highs and more frequent showers, contributing to a cooler and wetter (drizzly) summer atmosphere—notably different from earlier forecasts of heat and drought^[2].
• Localized variability: Although the general summer trend for Western Canada was predicted to be hot and dry due to a "heat dome" over the central U.S., in reality, there have been significant stretches of cooler and wetter weather in the Prairies, likely influenced by the location and persistence of broad weather systems and regional thunderstorms that track along the edge of the heat dome, also known as the "ring of fire" effect^[2][3][1].

It is worth noting that many initial seasonal forecasts anticipated a hotter and drier-than-average summer, but mid-season updates reflected increases in storm frequency, outbreaks of cooler air, and patchy, unpredictable rainfall—leading to the observed cool, drizzly conditions^[2][1].

In summary:
The drizzly, cool summer on the Canadian Prairies in 2025 can be attributed to a combination of an active, Pacific-influenced weather pattern with frequent disturbances, the presence of persistent upper-level troughs drawing in cooler air, and localized storm activity offsetting broader trends toward warmth and drought^[1][2]. These phenomena have resulted in more cloud, cooler temperatures, and drizzle, despite a general expectation of a hot, dry season.

⁂

• https://www.dtnpf.com/agriculture/web/ag/news/article/2025/07/18/will-active-pattern-hit-right-spots     
• https://www.theweathernetwork.com/en/news/weather/forecasts/canada-2025-summer-forecast-update    
• https://www.theweathernetwork.com/en/news/weather/seasonal/canada-2025-summer-forecast