Heavy rainfall across southern Quebec and the Outaouais region throughout the summer of 2026 has fundamentally shifted seasonal allergy patterns. While persistent precipitation has suppressed ragweed pollen, it has simultaneously created a breeding ground for mold, trading one respiratory trigger for another.
A Summer of Surplus Rain
The 2026 season stands in stark contrast to the previous year, which was defined by drought and lower-than-average rainfall. André Monette, a meteorologist at MétéoMédia, reports that the southern part of the province—specifically the Montreal area—saw 100 to 150 mm of rainfall above normal levels over the summer months.
The result is a noticeable drop in airborne irritants. Daniel Coates, director of business development and relations at Aerobiology Research Laboratories, explains that weeds like ragweed simply do not thrive in overly wet conditions. The rain also serves a mechanical purpose. Frequent showers act as a natural air filter, washing pollen from the atmosphere and lowering the concentration of allergens that typically plague residents in late summer and early fall.
The Rise of Autumn Mold Spores
Relief for pollen sufferers comes with a caveat. The moisture-rich environment has kept humidity levels high, providing the ideal conditions for mold spores to develop and disperse.
The risk is expected to climb as the season turns. As leaves fall and accumulate on the ground, the natural decomposition process will likely trigger a spike in mold spore counts. For those with mold sensitivities, this transition into late autumn may prove more difficult than the preceding months of the allergy season.
Strategies for Shifting Triggers
With environmental conditions in flux, health professionals are urging targeted management. Daniel Coates recommends that individuals experiencing symptoms first consult an allergist to confirm their specific triggers.
Residents can monitor these shifts in real time via the MétéoMédia application, which provides forecasted pollen concentrations by region. This allows for the adjustment of outdoor activities based on daily conditions. However, healthcare providers remain the primary resource for patients looking to map their specific allergy profiles and build long-term strategies for the changing seasons.
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