WeatherStory Allergy Index
A named, annual, fully transparent ranking of the 100 largest U.S. metropolitan areas by a modeled seasonal pollen-load index. Inspired by AAFA’s Allergy Capitals, but built from a published, reproducible seasonal model rather than a proprietary score — and refreshed every year.
Latest edition
WeatherStory Allergy Index 2026
100 metros ranked by seasonal pollen load, led by Cape Coral, FL (load index 57). Includes the top-20 ranked list, a season-onset map with a ZIP lookup, the full 100-metro table, and per-metro quotable lines. The median metro runs an active-pollen season of about 304 days.
What the index measures
For each metro, a seasonal model produces a 12-month intensity curve (0–4) for tree, grass, and ragweed pollen, shifted by latitude. Each type’s peak intensity is multiplied by how many months it stays in season, and the three products are summed into one load index. It is a model, not a measurement — a transparent alternative to static “allergy capitals” lists, not a copy of any proprietary score. Read the full formula and sources on the methodology page.
More pollen & allergy data
See the worst cities for allergies ranking, the pollen & allergy statistics hub, or browse pollen counts by city.