When is pollen worst in Des Moines?

The late-summer ragweed run is the headline in Des Moines: weed pollen peaks Aug–Nov, the longest and most punishing window of the year here. Tree pollen comes first (Mar–May) and grass bridges the gap (May–Jul), but it's the ragweed stretch that floors most sufferers. Currently, ragweed pollen is what's driving counts this month.

What's in the air in Des Moines right now?

In August, ragweed pollen is in season in Des Moines — the dominant allergen you're likely reacting to right now. A live count, when available, confirms the day's actual reading; this reflects the typical peak windows for Des Moines's continental Plains climate.

Is tree or grass pollen higher in Des Moines in spring?

In spring, tree pollen leads in Des Moines — trees pollinate Mar–May, ahead of grass (May–Jul). The handoff is the tail of the tree window: tree counts taper as grass climbs, so an early-spring flare is more likely tree pollen and a late-spring one more likely grass.

What makes Des Moines's pollen season distinctive?

Des Moines sits in the continental Plains zone, which means the country's worst ragweed — the continental Plains run a long, severe late-summer-into-fall weed season on top of the usual tree and grass peaks. That shapes when symptoms hit and which allergen to watch.

How do I reduce pollen exposure in Des Moines?

Through Des Moines's peak windows (tree Mar–May, grass May–Jul, ragweed Aug–Nov), keep windows shut and run AC on recirculate; counts run highest on dry, warm, windy mornings, so push outdoor activity to late afternoon or just after rain, which clears pollen from the air. A HEPA purifier indoors, a saline rinse after being outside, showering before bed, and starting antihistamines a week or two before your worst local window all measurably cut symptoms.

What pollen index counts as high?

Pollen is reported on a categorical scale — None, Low, Moderate, High, and Very High. "High" and above means most allergy sufferers notice symptoms even with brief outdoor exposure, and sensitized people should limit time outside and pre-medicate. "Low" to "Moderate" usually only affects highly sensitive individuals.

What is the allergy forecast in Des Moines today?

The allergy forecast is the airborne-pollen outlook that drives hay fever — exactly what this page tracks. Today's pollen level for Des Moines is shown above, broken into the tree, grass, and ragweed pollen behind most seasonal allergies. When the reading is High or Very High, plan for symptoms and pre-medicate; the seasonal calendar below shows which allergen leads in each part of the year.

Des Moines, Iowa Pollen Count & Allergy Forecast

Des Moines pollen count and allergy forecast — tree, grass, and ragweed seasons and what’s pollinating now

Des Moines, IA · Pollen season

In August, ragweed pollen is in season in Des Moines — the dominant allergen you're likely reacting to right now.

Based on the seasonal pollen calendar for this region.

Des Moines on the WeatherStory Allergy Index

Des Moines ranks #69 of 100 U.S. metros on the WeatherStory Allergy Index, with a modeled load index of 36 and a 274-day combined pollen season — its heaviest load is tree pollen, running 122 days.

#69of 100

Load index: 36
Combined season: 274 days
Heaviest load: Tree · 122 days

See the full 100 worst U.S. cities for pollen — a modeled seasonal load ranking (see methodology).

Typical now — Augustseasonal estimate, not a live reading

Ragweed pollen typically leads in Des Moines this time of year, at an estimated Moderate level. No live count is wired up; this reflects the seasonal calendar.

Pollen by type this season

TreeOut of seasonpeaks Mar–May
GrassOut of seasonpeaks May–Jul
Weed / RagweedIn seasonpeaks Aug–Nov

What pollinates near Des Moines

The tree, grass, and weed species that drive Des Moines’s pollen seasons, with each plant’s typical peak.

Trees

Oak Quercuspeaks April–May
Elm Ulmuspeaks March–April
Cottonwood Populus deltoidespeaks April–May
Hackberry Celtis occidentalispeaks April–May
Ash Fraxinuspeaks April–May

Grasses

Kentucky bluegrass Poa pratensispeaks May–June
Timothy Phleum pratensepeaks June–July
Smooth brome Bromus inermispeaks May–July
Johnson grass Sorghum halepensepeaks June–August

Weeds

Giant ragweed Ambrosia trifidapeaks August–October
Common ragweed Ambrosia artemisiifoliapeaks August–October
Pigweed Amaranthuspeaks August–September
Kochia Bassia scopariapeaks August–September
Lamb's quarters Chenopodium albumpeaks August–September

Species are the region’s common wind-pollinated plants; peak months are a seasonal estimate, not a measured count — see methodology.

Des Moines’s allergy year

Typical month-by-month pollen intensity for Des Moines, tuned to its latitude and climate region — darker means higher typical counts. The highlighted column is the current month.

JFMAMJJASOND

TreeMar–Jun

GrassMay–Aug

RagweedAug–Nov

How Des Moines compares to the U.S. average

Each colored bar is Des Moines’s typical season against the national-average window (grey). The offset is the per-city timing shift.

Treeabout average

Grassabout average

Ragweedabout average

“U.S. average” is the textbook tree Mar–May, grass May–Jul, ragweed Aug–Oct calendar. The shift is a phenology estimate (Hopkins’ bioclimatic law), not a measured count — see methodology.

How Des Moines’s pollen count works

The calendar above is tuned to Des Moines’s continental Plains climate, not a national average: tree pollen runs from week 10 (early March) to week 23 (early June), grass from week 18 (early May) to week 31 (early August), and ragweed from week 31 (early August) to week 44 (early November) here — a 274-day combined pollen season. Those windows are why ragweed pollen is the one in season in Des Moines right now.

No live count is wired up for Des Moines today, so the seasonal calendar above is your guide to which allergen is in season. Counts run highest on warm, dry, windy mornings and drop after rain, which washes pollen out of the air — reported on the None / Low / Moderate / High / Very High scale.

Frequently asked

When is pollen worst in Des Moines?: The late-summer ragweed run is the headline in Des Moines: weed pollen peaks Aug–Nov, the longest and most punishing window of the year here. Tree pollen comes first (Mar–May) and grass bridges the gap (May–Jul), but it's the ragweed stretch that floors most sufferers. Currently, ragweed pollen is what's driving counts this month.
What's in the air in Des Moines right now?: In August, ragweed pollen is in season in Des Moines — the dominant allergen you're likely reacting to right now. A live count, when available, confirms the day's actual reading; this reflects the typical peak windows for Des Moines's continental Plains climate.
Is tree or grass pollen higher in Des Moines in spring?: In spring, tree pollen leads in Des Moines — trees pollinate Mar–May, ahead of grass (May–Jul). The handoff is the tail of the tree window: tree counts taper as grass climbs, so an early-spring flare is more likely tree pollen and a late-spring one more likely grass.
What makes Des Moines's pollen season distinctive?: Des Moines sits in the continental Plains zone, which means the country's worst ragweed — the continental Plains run a long, severe late-summer-into-fall weed season on top of the usual tree and grass peaks. That shapes when symptoms hit and which allergen to watch.
How do I reduce pollen exposure in Des Moines?: Through Des Moines's peak windows (tree Mar–May, grass May–Jul, ragweed Aug–Nov), keep windows shut and run AC on recirculate; counts run highest on dry, warm, windy mornings, so push outdoor activity to late afternoon or just after rain, which clears pollen from the air. A HEPA purifier indoors, a saline rinse after being outside, showering before bed, and starting antihistamines a week or two before your worst local window all measurably cut symptoms.
What pollen index counts as high?: Pollen is reported on a categorical scale — None, Low, Moderate, High, and Very High. "High" and above means most allergy sufferers notice symptoms even with brief outdoor exposure, and sensitized people should limit time outside and pre-medicate. "Low" to "Moderate" usually only affects highly sensitive individuals.
What is the allergy forecast in Des Moines today?: The allergy forecast is the airborne-pollen outlook that drives hay fever — exactly what this page tracks. Today's pollen level for Des Moines is shown above, broken into the tree, grass, and ragweed pollen behind most seasonal allergies. When the reading is High or Very High, plan for symptoms and pre-medicate; the seasonal calendar below shows which allergen leads in each part of the year.

Pollen & allergy guides

For the science behind Des Moines’s pollen seasons — how counts are measured, when each type peaks, and what the numbers mean — see the pollen & allergy guides.

More for Des Moines

See the full Des Moines, IA weather forecast — hour-by-hour outlook, NOAA radar, satellite, and air quality.