Sneezing in spring? Itching in fall? Allergy season doesn’t hit every state the same way—or at the same time. What triggers symptoms in one region might be totally different just a few hundred miles away. If you’ve ever wondered why your allergies spike during certain months, where you live could be the key. Here’s what to know about allergy season across the U.S.
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Why Your Allergies Follow the Calendar: The Role of Location and Weather
Seasonal allergies don’t occur randomly—they follow a pattern that’s closely linked to your location and the time of year. That’s because allergy symptoms are often triggered by plant pollens, and the timing of pollination varies depending on regional climate and vegetation. In general, trees release pollen in the spring, grasses peak in the summer, and weeds like ragweed dominate in late summer and fall. This cycle means that your allergy season can look very different depending on where you live
Weather conditions also have a direct impact on how much pollen is in the air and how far it travels. Dry, windy days can cause pollen to spread more widely, increasing the chances of allergic reactions. On the other hand, rain can temporarily reduce pollen levels by washing particles out of the air. Humidity and temperature shifts further influence how intensely plants pollinate and how long the season lasts.
Adding to the challenge is the effect of climate change, which is making allergy seasons longer and more intense. Research shows that since 1970, the growing season in many parts of the U.S. has extended by several days. This means that plants have more time to produce pollen—resulting in longer periods of exposure for allergy sufferers and an extended calendar of discomfort in many regions.
Eastern Edge: What to Expect from Allergy Season in the Northeast & Southeast
Allergy season along the Eastern U.S. varies widely between the Northeast and Southeast, shaped by differences in climate, vegetation, and seasonal patterns. From New England to the Deep South, knowing what to expect—and when—can help you prepare for peak pollen times.
Northeast
In the Northeast, which includes areas like New York, Massachusetts, Pennsylvania, and Connecticut, allergy season typically begins in late winter or early spring. Tree pollens—especially birch, cedar, and maple—are the first to appear. As temperatures warm, grass pollens become more active in late spring and early summer, followed by weed pollens like ragweed in late summer and fall. Although cold winters often delay the start of allergy season, earlier springs and longer growing seasons due to warming temperatures have led to increased pollen exposure throughout the
Southeast
The Southeast—covering states like Georgia, Florida, North Carolina, and South Carolina—experiences a longer allergy season thanks to mild winters and extended warmth. Tree pollens such as oak, elm, and pine can start circulating as early as January or February. Grass pollens and mold become significant in spring and summer, while ragweed dominates in the fall. The higher humidity across much of the Southeast promotes mold growth, making allergens a nearly year-round concern in this region.
America’s Heartland: Navigating Allergy Peaks in the Midwest & South-Central
The central regions of the United States—spanning the Midwest and South-Central states—experience distinct allergy patterns shaped by their diverse climates and vegetation. Comprehending these seasonal shifts is primordial to managing symptoms more effectively throughout the year.
Midwest
In states like Illinois, Ohio, Michigan, and Minnesota, this season typically starts in the spring with tree pollens such as oak, birch, and cedar. As the season progresses, grass pollens take over in late spring and early summer, followed by a surge in ragweed during late summer and fall. Mold spores are also a concern, with levels fluctuating based on humidity. Climate change is already impacting the region—the freeze-free season has extended by approximately 13 days since 1970, leading to longer growing seasons and prolonged exposure.
South-Central
In the South-Central U.S., including states like Texas, Oklahoma, and Arkansas, this season can begin much earlier. Tree pollens like cedar and juniper may appear as early as December. Grass and weed pollens, including sagebrush and Russian thistle, are present through much of the year, especially in urban areas where landscaping encourages their growth. The region’s hot, dry summers and spring rainfall patterns strongly influence the timing and severity of allergy symptoms. Notably, “cedar fever“—a seasonal reaction to cedar pollen—is especially intense in areas such as central Texas.
Whether dealing with shifting seasons in the Midwest or year-round exposure in the South-Central region, staying informed about local patterns can help you better prepare for allergy peaks and minimize their impact.
Western Watch: Allergy Season Timing from the Southwest to the Pacific Coast
Allergy season in the western United States is shaped by dramatic regional contrasts, from the arid deserts of the Southwest to the damp forests of the Pacific Coast. These variations influence not only when pollen peaks occur, but also which allergens dominate the air.
Southwest
In states like Arizona, New Mexico, and parts of Nevada, the dry climate gives rise to distinct allergen patterns. Tree pollens—particularly from juniper, cedar, and oak—can begin circulating as early as December. Grasses and weeds, such as sagebrush and Russian thistle, contribute to year-round symptoms, especially in landscaped urban environments where these plants are common. The dry, windy conditions characteristic of the region help spread pollen widely, and the arid environment supports continuous pollen production from various species throughout much of the year.
Pacific Coast
Along the Pacific Coast, including areas like California, Oregon, and Washington, allergy seasons are influenced by the damp, temperate climate. In the Pacific Northwest, tree pollen season stretches from February to April, featuring allergens like alder, birch, and cedar. From May to July, grass pollen and mold spores become more prevalent, while weed pollen emerges in the fall. Meanwhile, California is experiencing the effects of climate change, with some cities reporting notable increases in pollen counts and a growing impact on allergy sufferers.
From the deserts to the coast, staying aware of local climate trends and regional allergens is essential to navigating allergy season in the western U.S.
Sources.
d’Amato, G., Annesi-Maesano, I., Urrutia-Pereira, M., Del Giacco, S., Rosario Filho, N. A., Chong-Neto, H. J., … & d’Amato, M. (2021). Thunderstorm allergy and asthma: state of the art. Multidisciplinary respiratory medicine, 16(1), 806.
Seth, D., & Bielory, L. (2021). Allergenic pollen season variations in the past two decades under changing climate in the United States. Immunology and Allergy Clinics, 41(1), 17-31.