Warmer winters and shifting weather patterns are extending pollen seasons, increasing high-pollen days, and raising the risk of more intense allergy symptoms.

Allergy sufferers may feel like their symptoms are hitting earlier and lasting longer, and the latest research and forecasting point to a worrying trend: the pollen season is changing—and in many places, it’s set to intensify.

Climate change is widely associated with more severe allergy conditions. in part because it can produce longer and more intense pollen seasons. according to a growing body of research from scientists and physicians.. Environmental health scientist Paul Beggs. a professor at Macquarie University in Sydney. discussed how climate change increases pollen in the atmosphere and alters exposure patterns. noting that it affects both how much pollen is present and when the season occurs.

Beggs. who published a 2024 paper on the link between climate change and asthma. said the shift is not just about higher pollen amounts.. It also changes the seasonality of pollen and the types of pollen people are exposed to. which matters for those whose bodies may react strongly to specific allergens.

With pollen season already underway across the United States, the AccuWeather 2026 U.S. Allergy Forecast predicts more high-pollen days this year. The forecast attributes these increases to factors such as storms and temperature swings, which can influence how and when plants release pollen.

AccuWeather climate expert and senior meteorologist Brett Anderson said the “seasonal allergy season” in America is expanding at both ends.. In other words. allergy timeframes are stretching beyond the traditional windows many people remember from previous years. increasing the likelihood that symptoms begin sooner or linger later.

Allergist and immunologist Dr.. Rebecca Saff of Massachusetts General Hospital in Boston agreed that the calendar of symptoms has shifted.. She pointed to warming driven by global temperature changes that can bring shorter. milder winters and warmer springs. which can effectively start allergy seasons earlier and stretch them later into the year.

Research published in 2022 in the journal Nature reinforces that expectation: it predicted pollen season would begin 40 days earlier and end 15 days later by the end of the century.. That kind of extension matters because longer seasons can mean more consistent exposure. increasing the chances that symptoms persist or become more disruptive over time.

Anderson linked the later end of the season to “later frost dates. ” explaining that when warmth and moisture coincide. trees. grass. and weeds can produce more pollen more often.. For people affected by seasonal allergies. this translates into a higher probability of repeated symptom flare-ups rather than a brief. contained period.

Temperature changes may also reshape which plants thrive in different regions.. Saff noted that warmer conditions can contribute to some species migrating north. including ragweed. which may replace allergens that people haven’t historically seen in certain areas.. That migration could help explain why new allergic triggers may become more common. such as allergens previously less prevalent in the Northeast.

Beyond length and distribution, experts are also raising concerns about extreme events.. Rising temperatures have been identified as a driver of more alarming extreme allergy events. and the World Meteorological Organization has reported that the past 11 years have been the 11 warmest on record.. When the climate shifts toward more frequent heat and volatile weather patterns. the allergy calendar can become less predictable—and potentially more intense.

The scale of the problem is already clear.. The U.S.. Centers for Disease Control and Prevention reported that 30% of Americans over the age of 18 have seasonal allergies.. With climate change reshaping pollen dynamics. the expectation is that symptoms such as watery eyes. sneezing. and coughing could last longer for many people.

For households planning around allergy seasons, the changing pattern can have practical consequences.. Longer pollen exposure increases the window when medications and preventative strategies may be needed. and it also raises the chance of symptoms disrupting sleep. school. work. and day-to-day routines.

The forecasts and research together also underline a broader point: allergy management may increasingly depend on weather risk rather than fixed seasons.. Storms. temperature swings. and shifting plant behavior can alter when pollen peaks. so people may need to respond as conditions evolve rather than relying on the traditional spring-or-fall timeline.

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