OR · Allergy Season Guide
Gresham Allergy Season Guide
PollyMap is actively seeking a qualified local collection partner in Gresham. This guide uses regional climate and historical allergen data while we recruit a local host.
PollyMap is actively looking for a qualified local partner in Gresham.
We're recruiting a qualified local allergy clinic, naturopathic clinic, university, environmental health professional, or other qualified organization to become the official pollen collection partner for Gresham.
Become the Official PollyMap Partner for GreshamSummary
PollyMap does not yet have weekly collected pollen data for Gresham. This guide is based on regional climate patterns and historical allergen data while we recruit a local collection partner. Tree pollen peaks in spring, grass pollen in late spring and early summer, and weed pollen in late summer and fall.
Local allergy guide for Gresham
Gresham shares Oregon's a cool, wet maritime climate with mild summers, rainy winters, and high year-round humidity. at 325 ft elevation.
Gresham at 325 ft elevation sits within Oregon's broader regional climate.
In Gresham, tree pollen — including Alder, Birch, Cedar — typically dominates from late winter through spring. Rye grass is the most common warm-season pollinator, and Plantain drives the largest fall pollen load.
Gresham's local mold profile includes Cladosporium, Alternaria, Penicillium. Spore counts tend to peak after rainfall and during the warm, humid portion of the year.
Local weather — temperature, rainfall, wind, and humidity — drives day-to-day pollen levels. Dry, windy days following warm weather typically produce the highest counts, while heavy rain temporarily clears the air.
Gresham monthly allergy calendar
Typical month-by-month intensity for the four major airborne allergen categories in Gresham.
| 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 |
Most common airborne molds
Current PollyMap data for Gresham
Official PollyMap Partner in Gresham
Frequently asked questions about allergies in Gresham
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Related guides
State Guide
Oregon Allergy Season Guide
Nearby city
Portland Allergy Season Guide
Nearby city
Eugene Allergy Season Guide
Nearby city
Salem Allergy Season Guide
Nearby city
Hillsboro Allergy Season Guide
Library
Pollen species library
Library
Mold species library
Reports
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