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Grass Pollen Stays Widespread as Reno Climbs and Texas Mold Intensifies

June 20, 2026 by PollenScience Staff

National Overview

Grass pollen remains the most widespread outdoor allergy burden. The West had the sharpest pressure, with Eugene and Seattle still Very High; Colorado Springs stayed high and Reno climbed into the high range. Midwest grass stayed elevated in Chicago and Greenfield, though La Crosse and Madison slipped below high levels, and South Central grass remained steady around Oklahoma City and Waco.

Elsewhere, grass was more local than regional. Olean remained elevated in western New York, Greenville stayed high in South Carolina, and most available Southeast stations were below the high range after Nashville dropped. Puerto Rico's available readings showed tree pollen, rather than grass, as the active burden.

Mold was the other important problem for sufferers, especially in Texas. San Antonio East reached Very High, Austin remained high, and Houston and Oklahoma City moved upward into moderate mold levels. Chicago mold also stayed high, while St. Louis dropped below that mark.

Tree pollen is now a narrower late-season issue. The remaining high readings were in Fairbanks, Colorado Springs, Lebanon, Caguas, and San Juan. Western tree pollen slipped lower in Anchorage South, Reno, and Seattle, even as Colorado Springs and Fairbanks stayed elevated. Weeds were broadly quiet, with Seattle's high nettle-family reading the main exception.

High Allergy Burden Locations

Location Allergen Level Drivers
Eugene, OR Grass Very High Grass Family, all types
San Antonio (East), TX Mold Very High Other identified fungi
Seattle, WA Grass Very High Grass Family, all types
Austin (Georgetown), TX Mold High Other identified fungi
Caguas (Centro), PR Tree High Other identified tree pollen
Chicago (Melrose Park), IL Grass High Grass Family, all types
Chicago (Melrose Park), IL Mold High Ascospores
Colorado Springs (North), CO Grass High Grass Family, all types
Colorado Springs (North), CO Tree High Pine Family with air bladders
Fairbanks, AK Tree High Pine Family with air bladders
Greenfield, WI Grass High Grass Family, all types
Greenville, SC Grass High Other identified grass pollen
Lebanon, NH Tree High Pine Family with air bladders
Oklahoma City, OK Grass High Grass Family, all types
Olean, NY Grass High Other identified grass pollen
Reno (Sparks), NV Grass High Grass Family, all types
San Juan, PR Tree High Other identified tree pollen
Seattle, WA Weed High Nettle family, Pellitory
Waco (Woodway South), TX Grass High Grass Family, all types

Pollen Drivers

Mold readings in Texas were led by other identified fungi, including San Antonio East and Austin. Chicago's high mold reading was driven by ascospores.

For trees, pine-family pollen accounted for the high readings in Fairbanks, Colorado Springs, and Lebanon. Puerto Rico's elevated tree readings were reported under the broader other-tree category. Weed pollen has not broadly started, but Seattle's high weed reading came from nettle-family and pellitory pollen.

Weather Context

The South Central region turned wetter and a bit cooler, which coincided with mold intensifying at San Antonio East and rising at Houston and Oklahoma City. Grass in the same region did not broadly change; Oklahoma City and Waco stayed high while other available Texas stations remained below that level.

The West was warmer and drier, which coincided with continued strong grass in Eugene and Seattle and Reno's move upward. Tree pollen in the West looked later-season and uneven: Fairbanks and Colorado Springs stayed high, while Anchorage South, Reno, and Seattle moved lower.

The Midwest cooled and received less rain than last week, matching the partial step-down in Wisconsin grass while Chicago and Greenfield stayed elevated. The Southeast also cooled slightly and remained wet, with Greenville the lone high grass station and most mold and tree readings staying low.

The Northeast was cooler but wetter and windier; allergy pressure stayed local, with Olean high for grass and Lebanon high for pine-family tree pollen. Puerto Rico weather was little changed, and Caguas and San Juan continued to carry high tree readings.

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