When is pollen worst in St. Charles?

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

What's in the air in St. Charles right now?

Right now grass pollen leads in St. Charles at a Moderate (3/5) level. The species actually in the air today: Pine, Oak, and Grasses. On a quiet live day, St. Charles's seasonal calendar fills in what's typically airborne this time of year.

Is tree or grass pollen higher in St. Charles in spring?

In spring, tree pollen leads in St. Charles — trees pollinate Feb–Apr, ahead of grass (Apr–Sep). 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 St. Charles's pollen season distinctive?

St. Charles sits in the warm, humid subtropical Southeast zone, which means an unusually long, overlapping season — the warm climate stretches grass across much of the year and pushes ragweed deep into autumn. That shapes when symptoms hit and which allergen to watch.

How do I reduce pollen exposure in St. Charles?

Through St. Charles's peak windows (tree Feb–Apr, grass Apr–Sep, 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.

St. Charles, Missouri Pollen Count

St. Charles pollen count and allergy forecast — tree, grass, and ragweed seasons and what’s pollinating now

St. Charles, MO · Pollen count right now

Grass pollen is Moderate in St. Charles today

Grass: Moderate 3/5Tomorrow: Moderate

Today’s pollen by type

TreeVery Low1/5
GrassModerate3/5
Weed / RagweedOut of season

Active now: Pine, Oak, Grasses.

St. Charles pollen calendar

Typical peak months for each pollen type in this climate region. The highlighted column is the current month.

JFMAMJJASOND

TreeFeb–Apr

GrassApr–Sep

WeedAug–Nov

Allergy relief

Zyrtec 24-Hour Allergy Relief (Cetirizine 10 mg)
A once-daily, non-drowsy oral antihistamine. Start it a couple of weeks before your worst pollen season for the best symptom control.
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NeilMed Sinus Rinse Kit (Saline Nasal Irrigation)
A saline rinse physically flushes pollen out of the nasal passages. Use it after time outdoors during peak season to cut the allergen load before symptoms build.
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How St. Charles’s pollen count works

The calendar above is tuned to St. Charles’s warm, humid subtropical Southeast climate, not a national average: tree pollen peaks Feb–Apr, grass Apr–Sep, and ragweed Aug–Nov here. Those windows are why grass pollen is the one in season in St. Charles right now.

Right now grass pollen leads in St. Charles at a Moderate (3/5) level. The species actually in the air today: Pine, Oak, and Grasses. 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 St. Charles?: The late-summer ragweed run is the headline in St. Charles: weed pollen peaks Aug–Nov, the longest and most punishing window of the year here. Tree pollen comes first (Feb–Apr) and grass bridges the gap (Apr–Sep), but it's the ragweed stretch that floors most sufferers. Currently, grass pollen is what's driving counts this month.
What's in the air in St. Charles right now?: Right now grass pollen leads in St. Charles at a Moderate (3/5) level. The species actually in the air today: Pine, Oak, and Grasses. On a quiet live day, St. Charles's seasonal calendar fills in what's typically airborne this time of year.
Is tree or grass pollen higher in St. Charles in spring?: In spring, tree pollen leads in St. Charles — trees pollinate Feb–Apr, ahead of grass (Apr–Sep). 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 St. Charles's pollen season distinctive?: St. Charles sits in the warm, humid subtropical Southeast zone, which means an unusually long, overlapping season — the warm climate stretches grass across much of the year and pushes ragweed deep into autumn. That shapes when symptoms hit and which allergen to watch.
How do I reduce pollen exposure in St. Charles?: Through St. Charles's peak windows (tree Feb–Apr, grass Apr–Sep, 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.

More for St. Charles

See the full St. Charles, MO weather forecast — hour-by-hour outlook, NOAA radar, satellite, and air quality.