From Grass to Ragweed: Ontario’s Allergy Season Is Just Getting Started
If you’ve found yourself sneezing, congested, or reaching for the allergy pills lately, you’re not alone — Ontario’s allergy season is in full swing, and this year, it’s coming in strong. A potent mix of recent rainfall followed by rising temperatures and dry winds has created the ideal conditions for trees, grass, and weeds to release a heavy wave of seasonal pollen across the province.
Experts are calling it a “perfect storm” for allergy sufferers. Dr. Mariam Hanna, a specialist in allergy, asthma, and immunology, told the Weather Network that warm weather and dry wind are key triggers for pollen release — and Ontario is entering prime conditions this week. Forecasts for early June show temperatures rising into the 20s, setting the stage for one of the most active allergy seasons in recent memory.
Tree pollen is peaking now, with birch, oak, ash, and maple leading the charge. While April and May are typically the worst months for tree allergens, the rainy spring has helped trees flourish — and now they’re letting loose. But it’s not just the trees. Grass pollen is gearing up to take over in June and July, and according to experts, this wave could be even longer-lasting than usual.
“We’re just getting into the season for grasses that will flower now too,” said Art Vanden Enden of Landscape Ontario. “And that’s going to be bad.” Warmer weather encourages grass growth, and mowing lawns only helps release more pollen into the air — a nightmare for those with allergies.
Dr. Hanna says patients of all ages are likely to see a spike in symptoms during grass pollen season, which traditionally stretches through the summer and worsens with outdoor activities like lawn maintenance.
But the season doesn’t end there. As summer starts to fade, ragweed pollen takes over — typically arriving in mid-August and staying until the cooler fall weather sets in. Ragweed is one of the most aggressive and widespread allergens, especially for those living in southern Ontario and into Quebec. Although ragweed doesn’t grow natively in Canada, its pollen travels easily from the U.S., particularly from rural regions in the Midwest and eastern states.
Climate change, experts warn, is making the ragweed season longer and more intense. According to the Asthma and Allergy Foundation of America, increased carbon dioxide levels are causing ragweed plants to grow faster and produce more pollen than ever before — bad news for allergy sufferers across the continent.
Currently, Ontario’s pollen forecast is at a moderate level, but experts say this is only the beginning. For those looking to stay ahead, pollen levels can be tracked daily through platforms like The Weather Network, Klarify, or IQAir’s AirVisual.
Whether you’re dodging tree pollen in June or bracing for ragweed in August, Ontario residents should prepare for a challenging allergy season ahead — and keep the tissues, antihistamines, and air filters close at hand.