When is pollen worst in Allentown?

Allentown runs the classic three-wave calendar: tree pollen Mar–May, grass May–Jul, then ragweed Aug–Oct. The two worst stretches are the spring tree peak and the late-summer ragweed peak. Currently, ragweed pollen is in season.

What's in the air in Allentown right now?

In September, ragweed pollen is in season in Allentown, peaking Aug–Oct. On Allentown's cold-temperate Northeast calendar the typical September level is High, led by ragweed pollen — a seasonal estimate, not a live count.

Is tree or grass pollen higher in Allentown in spring?

In spring, tree pollen leads in Allentown — 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 Allentown's pollen season distinctive?

Allentown sits in the cold-temperate Northeast zone, which means a sharply defined calendar — a hard winter lull, then a compact spring tree burst before grass and a long ragweed fall. That shapes when symptoms hit and which allergen to watch.

How do I reduce pollen exposure in Allentown?

Through Allentown's peak windows (tree Mar–May, grass May–Jul, ragweed Aug–Oct), 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.

When does the next pollen season start in Allentown?

Tree pollen is next in Allentown: it opens around week 10 (early March), peaks around week 15, and runs about 91 days.

What is the allergy forecast in Allentown today?

With no live reading for Allentown today, its allergy forecast is the seasonal estimate above: a typical September level of High, led by ragweed pollen.

Allentown, Pennsylvania Pollen Count & Allergy Forecast

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

Allentown, PA · Pollen season

In September, ragweed pollen is in season in Allentown, peaking Aug–Oct.

Based on the seasonal pollen calendar for this region.

Allentown on the WeatherStory Allergy Index

Allentown ranks #61 of 100 U.S. metros on the WeatherStory Allergy Index, with a modeled load index of 30 and a 244-day combined pollen season — its heaviest load is tree pollen, running 91 days.

#61of 100

Load index: 30
Combined season: 244 days
Heaviest load: Tree · 91 days

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

Typical now — Septemberseasonal estimate, not a live reading

Ragweed pollen typically leads in Allentown in September, at an estimated High level.

Pollen by type this season

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

What pollinates near Allentown

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

Trees

Oak Quercuspeaks April–May
Birch Betulapeaks April–May
Maple Acerpeaks March–April
Elm Ulmuspeaks March–April
Ash Fraxinuspeaks April–May

Grasses

Timothy Phleum pratensepeaks June–July
Kentucky bluegrass Poa pratensispeaks May–June
Orchard grass Dactylis glomeratapeaks June–July
Perennial ryegrass Lolium perennepeaks June–July

Weeds

Common ragweed Ambrosia artemisiifoliapeaks August–September
Giant ragweed Ambrosia trifidapeaks August–September
Lamb's quarters Chenopodium albumpeaks August–September
Plantain Plantagopeaks June–August

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

Allentown’s allergy year

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

JFMAMJJASOND

TreeMar–May

GrassMay–Jul

RagweedAug–Oct

How Allentown compares to the U.S. average

Each colored bar is Allentown’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 Allentown’s pollen count works

The calendar above is tuned to Allentown’s cold-temperate Northeast climate, not a national average: tree pollen runs from week 10 (early March) to week 22 (late May), grass from week 18 (early May) to week 30 (late July), and ragweed from week 31 (early August) to week 43 (late October) here — a 244-day combined pollen season. Those windows are why ragweed pollen is the one in season in Allentown right now.

No live count is wired up for Allentown today, so the seasonal calendar above is your guide to which allergen is in season.

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

Frequently asked

When is pollen worst in Allentown?: Allentown runs the classic three-wave calendar: tree pollen Mar–May, grass May–Jul, then ragweed Aug–Oct. The two worst stretches are the spring tree peak and the late-summer ragweed peak. Currently, ragweed pollen is in season.
What's in the air in Allentown right now?: In September, ragweed pollen is in season in Allentown, peaking Aug–Oct. On Allentown's cold-temperate Northeast calendar the typical September level is High, led by ragweed pollen — a seasonal estimate, not a live count.
Is tree or grass pollen higher in Allentown in spring?: In spring, tree pollen leads in Allentown — 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 Allentown's pollen season distinctive?: Allentown sits in the cold-temperate Northeast zone, which means a sharply defined calendar — a hard winter lull, then a compact spring tree burst before grass and a long ragweed fall. That shapes when symptoms hit and which allergen to watch.
How do I reduce pollen exposure in Allentown?: Through Allentown's peak windows (tree Mar–May, grass May–Jul, ragweed Aug–Oct), 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.
When does the next pollen season start in Allentown?: Tree pollen is next in Allentown: it opens around week 10 (early March), peaks around week 15, and runs about 91 days.
What is the allergy forecast in Allentown today?: With no live reading for Allentown today, its allergy forecast is the seasonal estimate above: a typical September level of High, led by ragweed pollen.