WA · Allergy Season Guide
Washington Allergy Season Guide
Washington experiences a cool, wet maritime climate with mild summers, rainy winters, and high year-round humidity.
Summary
Washington has 0 active PollyMap collection sites, and is seeking partners in 5 additional cities. Tree pollen typically dominates early spring, grass pollen peaks in late spring and early summer, and weed pollen (including ragweed) extends from late summer through fall.
PollyMap collection status across Washington
Statewide allergy overview
Washington experiences a cool, wet maritime climate with mild summers, rainy winters, and high year-round humidity.
Alder, birch, and cedar lead a strong late-winter and early-spring tree season. Grass pollen is intense from May through July, and the Willamette and Puget lowlands are among the heaviest grass pollen regions in North America.
Persistent rain and overcast skies produce some of the highest mold spore counts in the country, especially Cladosporium and Alternaria from fall through spring.
Allergy patterns vary by elevation and proximity to coast or mountains within Washington, but most of the state shares a common seasonal rhythm of spring tree pollen, summer grass pollen, and late-summer to fall weed pollen.
Washington allergy calendar
Month-by-month intensity for the four major airborne allergen categories.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Tree | High | V.High | V.High | High | Mod | Low | Low | Low | Low | Low | Mod | Mod |
| Grass | — | Low | Mod | High | V.High | V.High | High | Mod | Low | Low | Low | — |
| Weed | Low | Low | Mod | Mod | Mod | Mod | High | High | High | Mod | Low | Low |
| Mold | High | High | Mod | Mod | Low | Low | Low | Mod | Mod | High | V.High | High |
Top airborne molds
Major city guides in Washington
Latest PollyMap reports for Washington
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