Spring Allergy Statistics in US 2026 | Pollen, Season & Facts

Spring Allergy Season in America 2026

Spring in America no longer arrives the way it used to — and for the more than 67 million Americans who suffer from allergy symptoms, that is not a poetic observation. It is a public health crisis measured in sneezes, emergency room visits, missed workdays, and billions of dollars in healthcare spending. As of 2026, the Asthma and Allergy Foundation of America (AAFA) has declared the worsening spring allergy landscape “a public health emergency fueled by climate change” — language the organization’s president and CEO Kenneth Mendez used in March 2026 when releasing the AAFA’s 2026 Allergy Capitals report. The data behind that declaration is unambiguous: pollen seasons across North America have lengthened by an average of 20 days since 1990, pollen concentrations have increased by 21% over the same period according to a landmark PNAS study, and the freeze-free growing season has now extended by an average of 21 days across 87% of 198 US cities analyzed by Climate Central between 1970 and 2025. Warmer winters, earlier springs, and rising atmospheric CO2 have combined to produce a pollen environment that is more intense, longer lasting, and geographically broader than at any point in recorded US history.

What makes spring allergy statistics in 2026 particularly striking is the geographic upheaval visible in this year’s data. For years, the Southeast United States dominated the allergy capitals rankings — its warm, humid climate giving trees, grasses, and weeds a head start on pollen season. But the AAFA’s 2026 Allergy Capitals report, released March 2026, delivers a dramatic plot twist: for the first time ever, Boise, Idaho, ranked as the most challenging city in the US for pollen allergies. Multiple Western cities — historically considered mild allergy zones — have surged into the top 20 for the first time. Colorado Springs jumped from #84 in 2025 to #15 in 2026. Denver leapt from #91 to #30. Climate-driven spikes in grass and weed pollen, combined with atmospheric rivers, persistent drought, and warm sunny days that keep pollen airborne for longer, have reshuffled the allergy map. A quarter of adults and 20% of children and adolescents in the US have a diagnosed seasonal allergy, according to 2024 reports by the CDC’s National Center for Health Statistics. Behind every percentage point is a person reaching for an antihistamine before they even step outside.

Key Spring Allergy Facts in the US 2026

Source: AAFA 2026 Allergy Capitals Report (March 2026); CDC/NCHS FastStats Allergies (January 9, 2026); Climate Central “Warmer Growing Season, Longer Allergy Season” (March 4, 2026); PNAS “Anthropogenic Climate Change Is Worsening North American Pollen Seasons” (2021); Nature Communications pollen projection study (2022); Healio (April 8, 2026); SingleCare Allergy Statistics 2026 (March 27, 2026); Pollen.com; AllerVie Health / Medical Economics (March 22, 2026)

The key facts table for spring allergies in 2026 is a snapshot of a system under accelerating stress. The 67 million Americans suffering from allergy symptoms — a figure that encompasses all allergy types — and the 106 million Americans with allergies or asthma combined represent a population greater than one-third of the entire country dealing with immune system responses that are becoming more severe, more prolonged, and harder to manage with conventional antihistamines. The gender gap in seasonal allergy prevalence is one of the more underreported data points: 30% of women have seasonal allergies compared to 21% of men, a nearly 10-percentage-point difference that researchers link to hormonal influences on immune function. The age gradient is equally important: contrary to the popular assumption that children are most affected, it is adults aged 45–65 who show the highest prevalence at 27.7%, followed by adults aged 65–74 at 25.5%. Adults in their prime working years — the backbone of workforce productivity — are disproportionately bearing the allergy burden.

The climate data embedded in this table is not background context. It is the central driver of every trend visible in spring allergy statistics for 2026. The PNAS landmark study — analyzing 60 North American pollen stations across 821 site-years from 1990 to 2018 — found that human-caused warming drove pollen seasons 20 days longer and pollen concentrations 21% higher. Climate Central’s 2026 analysis updated that picture with fresh data: the freeze-free growing season has extended by 21 days on average across 87% of 198 US cities between 1970 and 2025, with the Northwest leading all US climate regions in growing season expansion. Where trees, grasses, and weeds once had a biologically fixed window in which temperatures permitted pollen release, that window has expanded at both ends simultaneously — earlier springs and later first frosts — creating conditions where some parts of the US now experience some form of allergenic pollen year-round, a reality that would have been considered extreme even a decade ago.

Spring Pollen Season Start Dates & Duration in the US 2026

SPRING POLLEN SEASON — START, PEAK & DURATION BY REGION (US 2026)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  Gulf Coast / Southeast    ██ Jan–Feb start  → Peak: Mar–Apr  → Longest season
  California / Southwest    ██ Feb–Mar start  → Peak: Mar–May  → Year-round risk
  Ohio Valley               ████████████████  Peak: Mid-April  → 11-state impact zone
  Pacific Northwest         ████████          Earlier 2026 start; high tree pollen
  Northern Plains           ████              Grass pollen surge: June–July 2026
  Great Lakes               ████              Grass pollen spike: June–July 2026
  New England               ███               Below-average tree pollen in 2026
  Rockies (CO, UT, ID)      ██████████████    Above-average; historic jumps in rankings
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  Tree pollen peaks: Eastern US late April | Evergreen peaks: May (Eastern + Western US)

Source: Climate Central “Warmer Growing Season, Longer Allergy Season” (March 4, 2026); Newsweek “Map Reveals Top 20 Worst Areas for Pollen Allergies in 2026” (March 31, 2026); AccuWeather via Newsweek (March 2026); Advisory.com “Allergy Season Is Back” (March 26, 2026); Inside Climate News (May 8, 2026)

The regional pollen season data for 2026 tells a story of simultaneous expansion in all directions — earlier in the South, more intense in the West, earlier in the Midwest, and overlapping into summer. The Ohio River Valley designation as one of the hardest-hit regions by mid-April — affecting millions across 11 states — is a recurring forecast feature that reflects the valley’s geography: warm air masses that accelerate tree pollination, combined with geographic containment that keeps pollen concentrations elevated longer than in open terrain. The Pacific Northwest’s earlier-than-usual tree pollen start in 2026 continues a multi-year trend that AccuWeather’s senior meteorologist Alan Reppert linked explicitly to temperature and rainfall patterns: “Weather conditions in your neighborhood and even hundreds of miles away can significantly influence pollen levels and allergy symptoms.”

The Rocky Mountain West’s dramatic upward movement in the 2026 allergy rankings deserves particular attention because it represents the clearest evidence of the geographic redistribution of allergy burden driven by climate change. Boise, Idaho — at the very top of the 2026 AAFA Allergy Capitals list for the first time — experienced spikes in grass and weed pollen driven by factors specific to its local climate: warm and sunny days combined with persistent wind that keeps pollen suspended in the air longer than in more humid or calmer climates. Colorado Springs’ jump from #84 to #15 in a single year is statistically remarkable — a 69-rank improvement (in the wrong direction for residents) — caused by tree pollen peaking earlier and higher, grass pollen lasting longer, and weed pollen starting earlier and reaching higher concentrations. The AAFA noted that atmospheric rivers, climate-change-driven warm temperatures, and drought were the primary environmental drivers of these Western city jumps. For residents of cities like Boise, Provo, San Diego, Wichita, and Rochester — all newly prominent in the 2026 top 20 — this is not an abstraction. It is a fundamental change in what it means to live there.

AAFA 2026 Allergy Capitals — Worst & Best Cities in the US 2026

AAFA 2026 ALLERGY CAPITALS — TOP 10 WORST US CITIES FOR POLLEN ALLERGIES
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  #1   Boise, ID          ████████████████████████████████  FIRST TIME #1
  #2   San Diego, CA      ████████████████████████████████  New top-5 entry
  #3   Tulsa, OK          ████████████████████████████████
  #4   Provo, UT          ████████████████████████████████  Western surge
  #5   Rochester, NY      ███████████████████████████████
  #6   Wichita, KS        ███████████████████████████████
  #7–10 Multiple cities   ██████████████████████████████
  #15  Colorado Springs   ██████████████████████   Up from #84 in 2025
  #30  Denver, CO         ████████████████         Up from #91 in 2025
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  Rankings based on: tree/grass/weed pollen scores + OTC med use + allergist access

Source: AAFA 2026 Allergy Capitals Report PDF (March 5, 2026); Fox31 Denver / KDVR (March 14, 2026); Healthline “Top 20 Worst US Cities for Spring Allergies in 2026” (April 8, 2026); Fox Weather (March 11, 2026); Advisory.com (March 26, 2026)

The 2026 AAFA Allergy Capitals report is, by every objective measure, the most geographically disruptive edition of the annual ranking since its inception. The elevation of Boise, Idaho to the #1 position — a city that many allergy sufferers might not have flagged as a concern even five years ago — is the clearest single data point showing how rapidly the allergy landscape is shifting under climate influence. The AAFA’s methodology is rigorous: rankings are based on pollen scores for tree, grass, and weed pollen combined, over-the-counter allergy medication use rates, and the number of board-certified allergists available relative to the affected population. A city scores poorly by having high pollen, high medication use, and inadequate access to specialist care — a combination that creates both health burden and treatment gaps simultaneously. The Western cities’ surge into the top 20 reflects that all three factors have worsened concurrently in those regions.

The Colorado data is perhaps the most startling story within the 2026 rankings. Colorado Springs’ 69-rank jump in a single year — from #84 in 2025 to #15 in 2026 — is driven by the confluence of three simultaneous worsening trends: tree pollen peaking earlier and higher, grass pollen lasting longer into summer, and weed pollen starting earlier and reaching higher peak concentrations. The state’s characteristic combination of warm sunny days and persistent wind — normally celebrated as a feature of Colorado living — is precisely the meteorological environment that keeps pollen suspended in the air column for extended periods, maximizing inhalation exposure. The AAFA specifically identified atmospheric rivers, climate-driven warm temperatures, and drought as the forcing factors behind the Western surge. Meanwhile, New England’s relative relief in 2026 — with below-average tree pollen due to a cooler spring — illustrates that the picture is not uniformly worse everywhere, but that the variance itself is increasing: some regions get a better-than-average year while others experience their worst on record, and the overall trend remains decisively upward.

Climate Change, Pollen, and Allergy Season Trends in the US 2026

CLIMATE CHANGE IMPACT ON US POLLEN SEASONS — KEY DATA (2026)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  Pollen season lengthening (1990–2018):      +20 days — PNAS (2021)
  Pollen concentration increase:              +21% — PNAS (2021)
  Growing season extension (1970–2025):       +21 days avg — Climate Central (2026)
  Cities with longer growing season:          87% of 198 US cities analyzed
  Climate change share of season lengthening: ~50% of observed increase
  Climate change share of concentration rise: ~8% of observed increase
  End-of-century pollen projection:           Up to +200% with continued CO2
  Urban heat island amplification:            Warmer cities = even longer seasons
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Source: PNAS “Anthropogenic Climate Change Is Worsening North American Pollen Seasons” (2021); Nature Communications (March 2022); Climate Central “Warmer Growing Season, Longer Allergy Season” (March 4, 2026); AAFA 2026 Allergy Capitals Report (March 5, 2026); Healio (April 8, 2026); Inside Climate News (May 8, 2026)

The science of climate change and pollen has moved from hypothesis to confirmed, quantified reality — and the 2026 data is the most current expression of a trend that stretches back decades. The PNAS study, which analyzed 60 North American stations across 821 site-years, found that human-caused climate change is the primary driver of both the 20-day lengthening and the 21% concentration increase in pollen seasons observed between 1990 and 2018. That study’s methodology was designed specifically to attribute the changes to anthropogenic warming rather than natural variability — and the attribution is statistically robust. Climate Central’s 2026 update extended the picture with real-time growing season data, confirming that the freeze-free season has lengthened in 87% of US cities analyzed, with the Northwest showing the largest regional gains. The urban heat island effect adds a compounding layer: in cities where the surrounding built environment retains more heat than rural areas, the growing season is even longer, and pollen production peaks even earlier and more intensely than regional averages suggest.

The end-of-century projection from Nature Communications is the number that should focus long-term attention: up to a 200% increase in pollen production under high-emission scenarios, driven by the compounding effects of longer growing seasons, temperature-driven increases in daily pollen emission maxima, and the direct stimulant effect of elevated CO2 on plant biology. That projection means the 67 million Americans currently suffering from allergy symptoms represents a fraction of the population that will be affected by mid-century and beyond if emission trajectories don’t change. The “thunderstorm asthma” phenomenon — where storms rupture pollen grains into ultrafine particles that penetrate deeper into the lungs than intact pollen — adds a qualitative dimension to the quantitative data: not only are there more pollen particles, but extreme weather events are making some exposures more biologically dangerous than a simple count of pollen grains would suggest.

Economic and Health Impact of Spring Allergies in the US 2026

ECONOMIC BURDEN OF SPRING ALLERGIES — US 2026
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  Annual allergy cost (all types):     ████████████████████ ~$18 billion/year
  Annual asthma cost (linked):         ████████████████████████████████ ~$80 billion/year
  Missed workdays (allergies):         ~4 million days/year
  Productivity drop (peak pollen):     21% reduction
  Employer cost per employee (AR):     $587/year (allergic rhinitis alone)
  Quality of life impact (surveyed):   82% of allergy sufferers say allergies affect QoL
  Sleep disruption:                    41% say allergies prevent good sleep
  Hospitalization due to allergy:      14% of surveyed allergy sufferers hospitalized
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Source: AllerVie Health “The Rise in Pollen is Spiking Allergy Hospitalizations and Impacting the Economy” (March 22, 2026); Medical Economics (March 22, 2026); SingleCare Allergy Statistics 2026 (March 27, 2026); CDC allergy cost data; Hewitt Associates Wellness Inventory study; AAFA Facts and Figures (updated February 2026)

The economic burden of spring allergies in the United States in 2026 operates at a scale that most public health frameworks dramatically undercount — because the costs are largely invisible, distributed across millions of individual lost hours, reduced cognitive performance, and degraded sleep quality rather than concentrated in dramatic hospitalization events. The $18 billion annual allergy cost is the most commonly cited figure, but when combined with the $80 billion annual asthma burden — of which allergic asthma represents a substantial share — the true fiscal footprint of pollen-driven immune responses in the US economy is closer to $100 billion per year and growing. The 21% drop in worker productivity during peak pollen periods and the 4 million missed workdays annually are the most direct expressions of that cost in labor market terms. The Hewitt Associates workplace study finding — that allergic rhinitis costs employers $587 per affected employee per year, more than stress, depression, or anxiety individually — challenges the prevailing corporate assumption that allergies are a minor inconvenience rather than a significant driver of operational cost.

The quality-of-life data from SingleCare’s survey (March 27, 2026) transforms these aggregate statistics into human experience. The fact that 82% of people with allergies say they affect their quality of life — and that 41% report both sleep disruption and mood impact — connects the pollen count to sleep science, mental health, and daily functioning in ways that dollar figures alone don’t capture. Allergist Dr. Saema Tahir, speaking to Healio in April 2026, flagged the growing overlap between allergic rhinitis and sleep disruption as one of the most clinically significant trends she is observing: “Patients report fragmented sleep, increased nighttime awakenings and worsened daytime fatigue due to allergies — and untreated allergic inflammation can exacerbate conditions like obstructive sleep apnea.” The 34% of sufferers who report staying indoors to avoid outdoor allergens during peak pollen season represents a behavioral adaptation with its own downstream costs: reduced physical activity, social isolation, and diminished enjoyment of the spring season that is already getting longer and more intense every year.

Disclaimer: This research report is compiled from publicly available sources. While reasonable efforts have been made to ensure accuracy, no representation or warranty, express or implied, is given as to the completeness or reliability of the information. We accept no liability for any errors, omissions, losses, or damages of any kind arising from the use of this report.

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