US Pollen Season Data

Mesquite, palo verde, and introduced olive trees contribute to spring allergies.

Monsoon season brings humidity and associated mold growth to Arizona.

Bermuda grass is the primary grass allergen in Arizona's irrigated areas.

Ragweed, Russian thistle, and desert allergens have a long season in Arizona.

Bermuda grass, ryegrass, and fescue thrive in California's warm climate, producing extended pollen seasons.

Cedar, oak, and walnut trees produce heavy pollen in California's Central Valley and coastal regions.

Ragweed, sagebrush, and Russian thistle dominate late-season allergies in California.

Coastal fog and irrigation create conditions for mold in California valleys.

Ragweed and sagebrush produce significant fall pollen across the Colorado plains.

Dry climate keeps mold levels relatively low compared to humid states.

Cottonwood, juniper, and pine trees contribute to spring allergies along the Front Range.

Lower humidity means shorter but intense grass pollen seasons in Colorado.

Oak, cedar, and palm pollen season starts very early in Florida's subtropical climate.

Bahia grass and Bermuda grass produce pollen nearly year-round in South Florida.

Ragweed and other weed pollens extend through fall in Florida.

Florida's humidity makes it one of the worst states for mold allergies.

Bermuda grass and bahia grass produce extended pollen seasons in the South.

Ragweed season is intense throughout Georgia.

Pine pollen creates visible yellow coating on everything in Georgia each spring.

Southeastern humidity promotes year-round mold growth.

Tropical trees produce low-level pollen year-round in Hawaii.

Tropical grasses pollinate throughout the year.

Minimal ragweed in Hawaii — one of the best states for ragweed allergy sufferers.

Tropical humidity creates ideal mold conditions year-round.

Ragweed concentrations in the Midwest are among the highest in the nation.

Agricultural areas and humidity promote seasonal mold growth.

Elm, oak, and cottonwood trees produce spring pollen in Illinois.

Timothy and bluegrass are the primary grass allergens in the Midwest.

Birch, maple, and oak produce spring pollen after long winters.

Ragweed season is short but intense in the upper Midwest.

Lake-influenced humidity promotes seasonal mold growth.

Short but intense grass pollen season in Minnesota's brief summer.

Ragweed is the dominant fall allergen, particularly in the Hudson Valley and Long Island.

Warm, humid summers promote mold growth in leaf litter and soil across New York.

Birch, oak, and maple trees produce heavy spring pollen across New York State.

Timothy grass and bluegrass are primary grass allergens in New York.

Ohio is in the heart of the ragweed belt.

Agricultural areas promote seasonal mold.

Ohio's diverse forests produce heavy tree pollen in spring.

Bluegrass and timothy are common allergens.

Ragweed season is intense across Texas, particularly in the eastern half of the state.

Mountain cedar (Ashe juniper) triggers 'Cedar Fever' in Central Texas, one of the most severe allergy events in the US.

Long growing season means extended grass pollen exposure across Texas.

Humid Gulf Coast conditions promote year-round mold growth in southeastern Texas.

Alder, birch, and cedar trees produce heavy spring pollen in the Pacific Northwest.

Ragweed is less prevalent than in eastern states, but other weeds contribute.

Ryegrass and fescue thrive in Washington's mild, wet climate.

Pacific Northwest rain and humidity create ideal conditions for mold year-round.