WeatherStory Allergy Index 2026
The 100 largest U.S. metros, ranked by a modeled seasonal pollen-load index — tree, grass, and ragweed intensity multiplied by season length. Cape Coral, FL leads with a load index of 57. A transparent, always-current alternative to static “allergy capitals” lists.
Top 20 worst U.S. metros for allergies (2026)
- #1Cape Coral, FL57
- #2Miami, FL54
- #3San Juan, PR54
- #4Bonita Springs, FL54
- #5Orlando, FL49
- #6Dallas, TX49
- #7Tampa, FL49
- #8Indianapolis, IN49
- #9Cincinnati, OH49
- #10Kansas City, MO49
- #11Columbus, OH49
- #12Charlotte, NC49
- #13Nashville, TN49
- #14Raleigh, NC49
- #15Memphis, TN49
- #16Oklahoma City, OK49
- #17Fort Worth, TX49
- #18Tulsa, OK49
- #19Charleston, SC49
- #20Dayton, OH49
The 20 highest pollen-load U.S. metros
Each dot is a top-20 metro, shaded by its pollen-load rank (darkest = worst). The top 10 are labeled; contiguous U.S. plus the Alaska and Hawaii insets — Puerto Rico is ranked in the table but is outside this projection.
How the index is built
Every metro is assigned one of nine U.S. climate regions, and its tree and grass seasons are shifted by latitude — Hopkins’ bioclimatic law puts phenological events roughly four days later per degree north. That yields a 12-month intensity curve (0–4, from None to Very High) for each pollen type. We multiply each type’s peak intensity by the number of months it stays in season and sum tree, grass, and ragweed into the load index. This is a modeled seasonal pollen-load ranking — not a copy of AAFA’s proprietary Allergy Capitals score (which also weights over-the-counter medication use and allergist density), and not measured pollen counts. AAFA established the ranked-annual-report concept; this is a transparent, reproducible take on it. Full formula, thresholds, and sources: methodology.
What is a high pollen count?
A pollen count is measured in grains per cubic meter of air (grains/m³), averaged over 24 hours, and rated by the AAAAI National Allergy Bureau (NAB) on a Low → Very High scale. The thresholds differ by pollen type: grass counts as “High” at just 20 grains/m³, while tree pollen isn’t “High” until 90.
| Category | Tree | Grass | Weed (ragweed) |
|---|---|---|---|
| Low | 0–14 | 0–4 | 0–9 |
| Moderate | 15–89 | 5–19 | 10–49 |
| High | 90–1,499 | 20–199 | 50–499 |
| Very High | 1,500+ | 200+ | 500+ |
Those grains/m³ categories describe a single day’s measured count. The WeatherStory Allergy Index above is a different measure — a modeled seasonal load score that multiplies each pollen type’s peak intensity by how long its season runs, so it ranks metros over a whole year rather than one day. For the full per-type ranges and the separate 0–12 pollen index, see the pollen & allergy statistics hub.
When does allergy season start?
As of mid-July 2026, spring tree pollen has finished across the Lower 48, grass pollen is at or just past its early-summer peak, and ragweed — the dominant fall allergen — is still about a month from its typical mid-August onset.
Allergy season starts earlier the farther south and west you live. The map colors each state by the typical first month of the year with active pollen among its ranked metros — as early as January in the warmest states. Enter your ZIP to see your nearest ranked metro’s onset month, worst allergen, and rank.
Pollen season calendar: when tree, grass & ragweed peak
Three pollen types hand off across the year in the same order almost everywhere in the U.S. — trees first, then grasses, then ragweed — each shifted earlier the farther south you live.
| Allergen | Season | Peak months |
|---|---|---|
| Tree | Late winter to late spring | March–May (as early as December–February in the warm South) |
| Grass | Late spring through summer | May–July (longer and later in the South and West) |
| Ragweed (weed) | Late summer through fall | August–October, ending at the first hard freeze (about 28°F) |
Windows are typical U.S. ranges (AAFA / ACAAI); local start dates shift with latitude and the year’s weather.
Quotable lines for the top 10 metros
One ready-to-cite sentence per metro. Copy with attribution to “WeatherStory Allergy Index 2026.”
- Cape Coral's grass pollen season runs 365 days, with a seasonal load index of 57 — #1 of 100 U.S. metros.
- Miami's grass pollen season runs 365 days, with a seasonal load index of 54 — #2 of 100 U.S. metros.
- San Juan's grass pollen season runs 365 days, with a seasonal load index of 54 — #3 of 100 U.S. metros.
- Bonita Springs's grass pollen season runs 365 days, with a seasonal load index of 54 — #4 of 100 U.S. metros.
- Orlando's grass pollen season runs 213 days, with a seasonal load index of 49 — #5 of 100 U.S. metros.
- Dallas's grass pollen season runs 213 days, with a seasonal load index of 49 — #6 of 100 U.S. metros.
- Tampa's grass pollen season runs 213 days, with a seasonal load index of 49 — #7 of 100 U.S. metros.
- Indianapolis's grass pollen season runs 213 days, with a seasonal load index of 49 — #8 of 100 U.S. metros.
- Cincinnati's grass pollen season runs 213 days, with a seasonal load index of 49 — #9 of 100 U.S. metros.
- Kansas City's grass pollen season runs 213 days, with a seasonal load index of 49 — #10 of 100 U.S. metros.
Full ranking: 100 U.S. metros
| # | Metro | Worst allergen | Season starts | Season length | Load index |
|---|---|---|---|---|---|
| 1 | Cape Coral, FL | Grass (year-round) | January | 365 days | 57 |
| 2 | Miami, FL | Grass (year-round) | January | 365 days | 54 |
| 3 | San Juan, PR | Grass (year-round) | January | 365 days | 54 |
| 4 | Bonita Springs, FL | Grass (year-round) | January | 365 days | 54 |
| 5 | Orlando, FL | Grass (Apr–Sep) | January | 335 days | 49 |
| 6 | Dallas, TX | Grass (Apr–Sep) | January | 335 days | 49 |
| 7 | Tampa, FL | Grass (Apr–Sep) | January | 335 days | 49 |
| 8 | Indianapolis, IN | Grass (Apr–Sep) | February | 304 days | 49 |
| 9 | Cincinnati, OH | Grass (Apr–Sep) | February | 304 days | 49 |
| 10 | Kansas City, MO | Grass (Apr–Sep) | February | 304 days | 49 |
| 11 | Columbus, OH | Grass (Apr–Sep) | February | 304 days | 49 |
| 12 | Charlotte, NC | Grass (Apr–Sep) | February | 304 days | 49 |
| 13 | Nashville, TN | Grass (Apr–Sep) | February | 304 days | 49 |
| 14 | Raleigh, NC | Grass (Apr–Sep) | February | 304 days | 49 |
| 15 | Memphis, TN | Grass (Apr–Sep) | February | 304 days | 49 |
| 16 | Oklahoma City, OK | Grass (Apr–Sep) | February | 304 days | 49 |
| 17 | Fort Worth, TX | Grass (Apr–Sep) | January | 335 days | 49 |
| 18 | Tulsa, OK | Grass (Apr–Sep) | February | 304 days | 49 |
| 19 | Charleston, SC | Grass (Apr–Sep) | January | 335 days | 49 |
| 20 | Dayton, OH | Grass (Apr–Sep) | February | 304 days | 49 |
| 21 | Knoxville, TN | Grass (Apr–Sep) | February | 304 days | 49 |
| 22 | Palm Bay, FL | Grass (Apr–Sep) | January | 335 days | 49 |
| 23 | Port St. Lucie, FL | Grass (Apr–Sep) | January | 335 days | 49 |
| 24 | Kissimmee, FL | Grass (Apr–Sep) | January | 335 days | 49 |
| 25 | Little Rock, AR | Grass (Apr–Sep) | February | 304 days | 49 |
| 26 | Houston, TX | Grass (Apr–Sep) | January | 335 days | 45 |
| 27 | St. Louis, MO | Grass (Apr–Sep) | February | 304 days | 45 |
| 28 | San Antonio, TX | Grass (Apr–Sep) | January | 335 days | 45 |
| 29 | Austin, TX | Grass (Apr–Sep) | January | 335 days | 45 |
| 30 | Virginia Beach, VA | Grass (Apr–Sep) | February | 304 days | 45 |
| 31 | Jacksonville, FL | Grass (Apr–Sep) | January | 335 days | 45 |
| 32 | Richmond, VA | Grass (Apr–Sep) | February | 304 days | 45 |
| 33 | Louisville, KY | Grass (Apr–Sep) | February | 304 days | 45 |
| 34 | New Orleans, LA | Grass (Apr–Sep) | January | 335 days | 45 |
| 35 | Baton Rouge, LA | Grass (Apr–Sep) | January | 335 days | 45 |
| 36 | Wichita, KS | Grass (Apr–Sep) | February | 304 days | 45 |
| 37 | Atlanta, GA | Grass (Apr–Sep) | February | 304 days | 42 |
| 38 | McAllen, TX | Grass (Apr–Sep) | January | 335 days | 42 |
| 39 | Birmingham, AL | Grass (Apr–Sep) | February | 304 days | 42 |
| 40 | Columbia, SC | Grass (Apr–Sep) | February | 304 days | 42 |
| 41 | Denton, TX | Grass (Apr–Sep) | February | 304 days | 42 |
| 42 | San Francisco, CA | Tree (Jan–Apr) | January | 304 days | 41 |
| 43 | Sacramento, CA | Tree (Jan–Apr) | January | 304 days | 41 |
| 44 | San Jose, CA | Tree (Jan–Apr) | January | 304 days | 41 |
| 45 | Fresno, CA | Tree (Jan–Apr) | January | 304 days | 41 |
| 46 | Concord, CA | Tree (Jan–Apr) | January | 304 days | 41 |
| 47 | San Diego, CA | Tree (Jan–Apr) | January | 304 days | 41 |
| 48 | Portland, OR | Grass (Apr–Jul) | January | 304 days | 41 |
| 49 | Bakersfield, CA | Tree (Jan–Apr) | January | 304 days | 41 |
| 50 | Reno, NV | Tree (Jan–Apr) | January | 304 days | 41 |
| 51 | Milwaukee, WI | Tree (Mar–May) | March | 244 days | 37 |
| 52 | Rochester, NY | Tree (Mar–May) | March | 244 days | 37 |
| 53 | Madison, WI | Tree (Mar–May) | March | 244 days | 37 |
| 54 | Chicago, IL | Tree (Mar–May) | March | 244 days | 37 |
| 55 | Washington, DC | Tree (Mar–May) | February | 274 days | 37 |
| 56 | Boston, MA | Tree (Mar–May) | March | 244 days | 37 |
| 57 | Detroit, MI | Tree (Mar–May) | March | 244 days | 37 |
| 58 | Baltimore, MD | Tree (Mar–May) | February | 274 days | 37 |
| 59 | Cleveland, OH | Tree (Mar–May) | March | 244 days | 37 |
| 60 | Providence, RI | Tree (Mar–May) | March | 244 days | 37 |
| 61 | Hartford, CT | Tree (Mar–May) | March | 244 days | 37 |
| 62 | Buffalo, NY | Tree (Mar–May) | March | 244 days | 37 |
| 63 | Grand Rapids, MI | Tree (Mar–May) | March | 244 days | 37 |
| 64 | Albany, NY | Tree (Mar–May) | March | 244 days | 37 |
| 65 | Worcester, MA | Tree (Mar–May) | March | 244 days | 37 |
| 66 | Toledo, OH | Tree (Mar–May) | March | 244 days | 37 |
| 67 | Minneapolis, MN | Tree (Mar–May) | March | 274 days | 36 |
| 68 | Omaha, NE | Tree (Mar–May) | March | 274 days | 36 |
| 69 | Des Moines, IA | Tree (Mar–May) | March | 274 days | 36 |
| 70 | Las Vegas, NV | Tree (Jan–Apr) | January | 304 days | 36 |
| 71 | Albuquerque, NM | Tree (Jan–Apr) | January | 304 days | 36 |
| 72 | Tucson, AZ | Tree (Jan–Apr) | January | 304 days | 36 |
| 73 | El Paso, TX | Tree (Jan–Apr) | January | 304 days | 36 |
| 74 | Salt Lake City, UT | Tree (Mar–May) | March | 244 days | 33 |
| 75 | Colorado Springs, CO | Tree (Mar–May) | February | 274 days | 33 |
| 76 | Ogden, UT | Tree (Mar–May) | March | 244 days | 33 |
| 77 | New York, NY | Tree (Mar–May) | March | 244 days | 30 |
| 78 | Los Angeles, CA | Tree (Jan–Apr) | January | 274 days | 30 |
| 79 | Seattle, WA | Tree (Feb–May) | February | 274 days | 30 |
| 80 | Brooklyn, NY | Tree (Mar–May) | March | 244 days | 30 |
| 81 | Queens, NY | Tree (Mar–May) | March | 244 days | 30 |
| 82 | Riverside, CA | Tree (Jan–Apr) | January | 274 days | 30 |
| 83 | Manhattan, NY | Tree (Mar–May) | March | 244 days | 30 |
| 84 | Mission Viejo, CA | Tree (Jan–Apr) | January | 274 days | 30 |
| 85 | Allentown, PA | Tree (Mar–May) | March | 244 days | 30 |
| 86 | Staten Island, NY | Tree (Mar–May) | March | 244 days | 30 |
| 87 | Long Beach, CA | Tree (Jan–Apr) | January | 274 days | 30 |
| 88 | Philadelphia, PA | Tree (Mar–May) | March | 244 days | 30 |
| 89 | Pittsburgh, PA | Tree (Mar–May) | March | 244 days | 30 |
| 90 | Bronx, NY | Tree (Mar–May) | March | 244 days | 30 |
| 91 | Bridgeport, CT | Tree (Mar–May) | March | 244 days | 30 |
| 92 | New Haven, CT | Tree (Mar–May) | March | 244 days | 30 |
| 93 | Akron, OH | Tree (Mar–May) | March | 244 days | 30 |
| 94 | Harrisburg, PA | Tree (Mar–May) | March | 244 days | 30 |
| 95 | Denver, CO | Tree (Mar–May) | March | 244 days | 27 |
| 96 | Provo, UT | Tree (Mar–May) | March | 244 days | 27 |
| 97 | Spokane, WA | Tree (Mar–May) | April | 213 days | 27 |
| 98 | Phoenix, AZ | Tree (Jan–Apr) | January | 274 days | 26 |
| 99 | Mesa, AZ | Tree (Jan–Apr) | January | 274 days | 26 |
| 100 | Boise, ID | Ragweed (Aug–Oct) | March | 244 days | 25 |
“Worst allergen” is the pollen type with the highest modeled load (peak intensity × season length) and its peak-month window. “Season starts” is the first month of the year with any active pollen; “season length” is the total active window across all three allergens. Load index = the sum of (peak × months in season) for tree, grass, and ragweed.
Frequently asked
- What is the WeatherStory Allergy Index?
- It is a modeled seasonal pollen-load ranking of the 100 largest U.S. metropolitan areas. For each metro it scores modeled tree, grass, and ragweed intensity against how long each season lasts, then sums the three into one load index. It is inspired by AAFA's long-running Allergy Capitals report but built from a transparent, always-current seasonal model rather than a proprietary yearly score.
- Is this the same as AAFA's Allergy Capitals?
- No. AAFA's Allergy Capitals report also weights over-the-counter allergy-medicine use and the number of board-certified allergists in each metro. The WeatherStory Allergy Index computes only modeled seasonal pollen load, from regional season windows and each city's latitude rather than measured daily counts. Read it as a related but different, transparently reproducible ranking — not a copy of AAFA's number.
- Which U.S. metro ranks #1 in 2026?
- Cape Coral, Florida tops the 2026 index with a seasonal load index of 57. Its worst allergen is grass, whose season runs about 365 days, and its overall active-pollen window spans roughly 365 days a year.
- When does allergy season start?
- It depends where you live, which is why this report includes an onset map. In the warm South and West, tree and grass pollen can be active as early as January; across the northern tier, tree pollen usually leads in March or April. The map colors each state by the typical first month of the year with active pollen among its ranked metros. Enter your ZIP to see your nearest metro's onset month.
- How long is the typical pollen season?
- Across the 100 ranked metros, the median active-pollen window — any of tree, grass, or ragweed at Low or above — is about 304 days, and 19 metros run a near-year-round season of 330+ days. Warm, humid metros that stack tree, grass, and ragweed back to back carry the longest seasons; short, cold, or dry climates carry the shortest.
- How accurate is the ranking?
- It is a model, not a measurement. The intensity values come from published regional season windows (AAFA/ACAAI) shifted by latitude (Hopkins' bioclimatic law), not from a pollen-counting station in each city, so treat small rank gaps between neighbors as noise, not precision. The value is transparency: the formula is published on the methodology page, so anyone can trace why a metro lands where it does.
- Can I republish the ranking?
- Yes — with attribution. Please credit "WeatherStory Allergy Index 2026 (weatherstory.io/allergy-index/2026)" and link the methodology page. A recommended citation line is provided at the bottom of this report.
Recommended citation
WeatherStory Allergy Index 2026. Weather Story, 2026-07-11. A modeled seasonal pollen-load ranking of the 100 largest U.S. metropolitan areas. https://weatherstory.io/allergy-index/2026. Methodology: https://weatherstory.io/methodology.
More pollen & allergy data
See the always-current worst cities for allergies ranking, the pollen & allergy statistics hub, or browse pollen counts by city for the full per-city tree, grass, and ragweed calendars.