Is it allergy season in Iowa?

Iowa's position in the heart of the American corn belt creates an outsized allergy burden, particularly for grass and ragweed sufferers. The state's flat topography provides no geographic barriers to pollen dispersal — wind events can carry pollen from southern Iowa to the Minnesota border in hours. Des Moines sits in one of the country's highest ragweed production zones. Tree pollen is significant in spring, but the grass and ragweed seasons define Iowa's allergy calendar.

Iowa's flat agricultural landscape means there's less regional variation than in most states. The primary differences are east-west: eastern Iowa along the Mississippi River corridor sees some additional tree diversity from the river-bottom forests, while western Iowa near Sioux City is more open and wind-swept, amplifying grass and weed pollen dispersal.

Des Moines Metro

Ragweed belt epicenter in the capital region

Des Moines sits in one of the highest ragweed production zones in the United States. The surrounding corn and soybean fields maintain disturbed soil edges where ragweed thrives. Tree pollen is significant in April–May; grass follows June–July; ragweed dominates August–September.

Trees · Apr–MayGrass · May–JulRagweed · Aug–Sep (intense)

Cedar Rapids / Iowa City

Mississippi River corridor tree diversity

Eastern Iowa's river-bottom forests along the Cedar and Iowa Rivers add variety to the tree pollen season, with cottonwood and elm adding to the oak and maple burden. Cedar Rapids and Iowa City experience a similar allergy profile to Des Moines but with slightly more tree diversity.

Trees · Apr–MayCottonwood · MayRagweed · Aug–Sep

Davenport / Quad Cities

Mississippi River and Illinois border influence

Davenport sits at the Iowa-Illinois border on the Mississippi, connecting it to the Quad Cities metro. River-bottom pollen from floodplain forests adds to the tree season. The urban corridor traps pollen on calm days. Ragweed is intense — similar to neighboring Illinois counts.

Trees · Apr–MayGrass · May–JulRagweed · Aug–Sep

Sioux City / Western Iowa

Open plains and wind-amplified dispersal

Sioux City's position at the Iowa-Nebraska-South Dakota border puts it on the edge of the Great Plains. The open terrain amplifies wind-driven grass and weed pollen dispersal. Prairie remnants add native grass species to the Timothy and orchard grass burden from agriculture.

Grass · May–Jul (plains)Ragweed · Aug–SepPrairie species

Each row shows a full year of pollen for one region — trees in blue, grasses in green, weeds in amber. Look for where all three rows go quiet at the same time — that's your window.

Oral Allergy Syndrome (also called pollen-food allergy syndrome) causes tingling or mild itching in the mouth when you eat certain raw foods during the relevant pollen season. The proteins in the food are similar enough to the pollen protein that your immune system cross-reacts. Cooking usually deactivates the offending protein, so the same food cooked may cause no reaction.

Oak & Birch pollen

Stone fruits & apples

Apples, peaches, cherries, plums, pears, almonds, hazelnuts, carrots, celery

Peak risk April–May in Iowa. The Mississippi River corridor adds birch diversity to the oak burden. OAS reactions are most common during the peak tree season in late April.

Grass pollen

Tomatoes, potatoes & melons

Tomatoes, potatoes, kiwi, watermelon, cantaloupe, oranges (in some cases)

Peak risk May–July. Iowa's agricultural landscape produces very high grass counts — both from Timothy and orchard grass in pastures and from native prairie remnants.

Ragweed

Melons & bananas

Watermelon, cantaloupe, honeydew, banana, zucchini, cucumber, sunflower seeds

Peak risk August–September. Iowa sits in the heart of the ragweed belt. Des Moines is one of the Midwest's highest ragweed cities. The flat terrain allows ragweed pollen to travel enormous distances.

Not medical advice. If you suspect OAS, speak with an allergist — it can sometimes progress, and symptoms that extend beyond the mouth should be evaluated.