When is pollen worst in Baltimore?

Baltimore 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 what's driving counts this month.

What's in the air in Baltimore right now?

In August, ragweed pollen is in season in Baltimore — 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 Baltimore's cold-temperate Northeast climate.

Is tree or grass pollen higher in Baltimore in spring?

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

Baltimore 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 Baltimore?

Through Baltimore'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.

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 Baltimore today?

The allergy forecast is the airborne-pollen outlook that drives hay fever — exactly what this page tracks. Today's pollen level for Baltimore 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.

Baltimore, Maryland Pollen Count & Allergy Forecast

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

Baltimore, MD · Pollen season

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

Based on the seasonal pollen calendar for this region.

Baltimore on the WeatherStory Allergy Index

Baltimore ranks #58 of 100 U.S. metros on the WeatherStory Allergy Index, with a modeled load index of 37 and a 274-day combined pollen season — its heaviest load is tree pollen, running 122 days.

#58of 100

Load index: 37
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 Baltimore 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–Oct

What pollinates near Baltimore

The tree, grass, and weed species that drive Baltimore’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.

Baltimore’s allergy year

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

JFMAMJJASOND

TreeFeb–May

GrassApr–Jul

RagweedAug–Oct

How Baltimore compares to the U.S. average

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

The calendar above is tuned to Baltimore’s cold-temperate Northeast climate, not a national average: tree pollen runs from week 5 (early February) to week 18 (early May), grass from week 14 (early April) to week 27 (early July), and ragweed from week 31 (early August) to week 40 (early October) here — a 274-day combined pollen season. Those windows are why ragweed pollen is the one in season in Baltimore right now.

No live count is wired up for Baltimore 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 Baltimore?: Baltimore 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 what's driving counts this month.
What's in the air in Baltimore right now?: In August, ragweed pollen is in season in Baltimore — 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 Baltimore's cold-temperate Northeast climate.
Is tree or grass pollen higher in Baltimore in spring?: In spring, tree pollen leads in Baltimore — 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 Baltimore's pollen season distinctive?: Baltimore 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 Baltimore?: Through Baltimore'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.
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 Baltimore today?: The allergy forecast is the airborne-pollen outlook that drives hay fever — exactly what this page tracks. Today's pollen level for Baltimore 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 Baltimore’s pollen seasons — how counts are measured, when each type peaks, and what the numbers mean — see the pollen & allergy guides.

More for Baltimore

See the full Baltimore, MD weather forecast — hour-by-hour outlook, NOAA radar, satellite, and air quality.