Is allergy season starting earlier? It depends where you live, according to experts

Undated photo of a person sneezing. (Photo by Andrea Piacquadio/Pexels)

With the start of spring comes the start of blooms … which comes the start of allergy season.

And while tree pollen starts releasing into the atmosphere in the early spring, followed by grass pollen in the late spring and early summer, some allergy sufferers may feel symptoms slightly earlier than that.

However, experts who spoke with CTVNews.ca explained the earlier start to allergy season depends on what part of the country you live in.

Dr. Anne Ellis is a professor of medicine and chairs the allergy and immunology division at Queens University. She said compared to five years ago, the spring pollen season has been starting earlier than it used to in some parts of the country, including British Columbia, which starts to see blooms as early as January.

However, in Ontario and Quebec, it’s been the opposite.

“We’ve had later starts,” she said. “As you can see with the nice dump of snow we had recently, there’s not going to be an early birch pollen season this year.”

Ellis added that the birch pollen season has typically started in the last week of April or first week of spring for the last five to seven years in Ontario. However, when the warm weather finally arrives, Ellis said that “kickstarts trees into realizing, ‘oh I should be pollinating by now.’”

“And so we’ve had very intense starts to the spring allergy season,” she said.

“Because winter has gone on for so long, when the warm weather finally comes, it seems to come on with a bit of a bang and it kickstarts the trees into realizing, ‘Oh, I should be pollinating by now,’” she explained.

To add to that severity is the start of grass pollen season, leading to a “double whammy where there’s an overlap between tree pollen season and grass pollen season.”

“People who are allergic to both, get hit really hard, come mid-May,” Ellis said.

Earlier starts in western B.C., delays in Ontario

Daniel Coates is the director of Aerobiology Research Laboratories in Ottawa, which researches and collects data on seasonal allergies across the country. He agreed that the start of the allergy season depends on where you live in the country.

For B.C. cities like Victoria and Vancouver, the pollen season started in late January and early February. But he said for other parts of the country, the season usually starts later, though the fluctuation in weather – with temperatures spiking and dropping quickly - has pushed it back.

“It’s delayed pollen season in a lot of areas like across the Prairies, into Manitoba,” he said. “Ontario has been a bit of a weird start because we had pollen earlier than it usually starts in Toronto, then it went back down and now it’s starting to pick back up again in the last two weeks.”

Pollen counts vary across country

Coates said Canada is also experiencing a lot more pollen in the air in the last few decades. In 1998, there were half a million grains of pollen in the air across the country, while currently there are almost a million grains. He credits longer, warmer seasons to the change, as more pollen is being produced and released into the air.

Anything more than 200 grains per cubic metre is considered a high day for pollen in Canada, he explained.

Coates added that Hamilton, Ont., has had the worst pollen in the country, with close to 8,300 grains per cubic metre, over the year until present day, compared to Ottawa, which had 130 grains.

In the last week in Toronto, there were 2,800 grains of pollen, which Coates said “is significant,” compared to the same time last year, which was 614. In 2024, for the same time of year, that number was 927, and in 2023 the number was 3,693.

Meanwhile, “nothing remarkable is happening yet” in Calgary, Edmonton, Saskatoon, Regina or Winnipeg, though he suspects that will change soon. He added the Atlantic provinces always start later, and don’t get massive amounts of pollen.

“If you have allergies, move to the Maritimes,” he joked.