Allergy Season in the Northwest Has Grown by 31 Days Since 1970, Outpacing Every Other U.S. Region

Allergy sufferers in the Pacific Northwest are facing a dramatically longer pollen season than previous generations, according to a new data analysis that finds the region's allergy season has expanded by 31 days since 1970 — the largest increase of any region in the United States.

The findings add to a growing body of evidence suggesting that climate change is fueling longer, more intense allergy seasons across the country. Warmer temperatures and shifting weather patterns are allowing plants to bloom earlier in the spring and continue releasing pollen later into the fall, extending the window of misery for millions of Americans.

The Northwest's 31-day increase stands out as particularly striking compared to other parts of the country. Researchers attribute the region's outsized growth to its unique combination of climate sensitivity, vegetation types, and the accelerated warming trends that have been recorded across the Pacific Northwest in recent decades.

Nationally, the trend is also moving in the wrong direction for allergy sufferers. Pollen seasons across the U.S. have grown longer and pollen concentrations have increased, meaning that people are not only exposed for more days each year but are also encountering higher levels of allergens when they are exposed.

Health experts warn that the expanding allergy season carries real public health consequences. Prolonged exposure to pollen is linked to increased rates of asthma attacks, respiratory infections, and reduced quality of life, with costs to the healthcare system running into the billions of dollars annually.

For residents of the Northwest, the data underscores the importance of planning ahead. Allergists recommend that patients begin preventive treatments earlier in the year and consult with healthcare providers about updated management strategies as seasonal windows continue to shift.