When is pollen worst in San Antonio?

The late-summer ragweed run is the headline in San Antonio: weed pollen peaks Aug–Nov, the longest and most punishing window of the year here. Tree pollen comes first (Dec–Mar) and grass bridges the gap (Mar–Aug), but it's the ragweed stretch that floors most sufferers. Currently, ragweed pollen is in season.

What's in the air in San Antonio right now?

In September, ragweed pollen is in season in San Antonio, peaking Aug–Nov. On San Antonio's warm, humid subtropical Southeast 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 San Antonio in spring?

In spring, tree pollen leads in San Antonio — trees pollinate Dec–Mar, ahead of grass (Mar–Aug). 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 San Antonio's pollen season distinctive?

San Antonio 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 San Antonio?

Through San Antonio's peak windows (tree Dec–Mar, grass Mar–Aug, 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.

When does the next pollen season start in San Antonio?

Tree pollen is next in San Antonio: it opens around week 49 (early December), peaks around week 2, and runs about 122 days.

What is the allergy forecast in San Antonio today?

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

San Antonio, Texas Pollen Count & Allergy Forecast

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

San Antonio, TX · Pollen season

In September, ragweed pollen is in season in San Antonio, peaking Aug–Nov.

Based on the seasonal pollen calendar for this region.

San Antonio on the WeatherStory Allergy Index

San Antonio ranks #6 of 100 U.S. metros on the WeatherStory Allergy Index, with a modeled load index of 46 and a 365-day combined pollen season — its heaviest load is grass pollen, running 183 days.

#6of 100

Load index: 46
Combined season: 365 days
Heaviest load: Grass · 183 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 San Antonio in September, at an estimated High level.

Pollen by type this season

TreeOut of seasonpeaks Dec–Mar
GrassOut of seasonpeaks Mar–Aug
Weed / RagweedIn seasonpeaks Aug–Nov

What pollinates near San Antonio

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

Trees

Mountain cedar (Ashe juniper) Juniperus asheipeaks December–February
Oak Quercuspeaks March–April
Loblolly pine Pinus taedapeaks March–April
Pecan Carya illinoinensispeaks April–May
Sweetgum Liquidambar styracifluapeaks March–April
Mulberry Moruspeaks March–April
Elm Ulmuspeaks February–March

Grasses

Bermuda grass Cynodon dactylonpeaks May–September
Bahia grass Paspalum notatumpeaks May–September
Johnson grass Sorghum halepensepeaks June–August
Timothy Phleum pratensepeaks May–June

Weeds

Common ragweed Ambrosia artemisiifoliapeaks August–October
Giant ragweed Ambrosia trifidapeaks August–October
Pigweed Amaranthuspeaks August–September
English plantain Plantago lanceolatapeaks May–September

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

San Antonio’s allergy year

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

JFMAMJJASOND

TreeDec–Mar

GrassMar–Aug

RagweedAug–Nov

How San Antonio compares to the U.S. average

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

Tree~7 wks earlier

Grass~7 wks earlier

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 San Antonio’s pollen count works

The calendar above is tuned to San Antonio’s warm, humid subtropical Southeast climate, not a national average: tree pollen runs from week 49 (early December) to week 13 (late March), grass from week 10 (early March) to week 35 (late August), and ragweed from week 31 (early August) to week 48 (late November) here — a 365-day combined pollen season. Those windows are why ragweed pollen is the one in season in San Antonio right now.

San Antonio also runs the winter tree season most of the country never sees: mountain cedar (Ashe juniper, Juniperus ashei) releases pollen from mid-December through February, peaking in mid-January and often set off by a cold front. The reaction is known locally as cedar fever, and it is why the tree window above opens in December here. The numbers stay modeled, not measured — see the cedar fever guide for the counts, the symptoms, and the sources.

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

For the science behind San Antonio’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 San Antonio?: The late-summer ragweed run is the headline in San Antonio: weed pollen peaks Aug–Nov, the longest and most punishing window of the year here. Tree pollen comes first (Dec–Mar) and grass bridges the gap (Mar–Aug), but it's the ragweed stretch that floors most sufferers. Currently, ragweed pollen is in season.
What's in the air in San Antonio right now?: In September, ragweed pollen is in season in San Antonio, peaking Aug–Nov. On San Antonio's warm, humid subtropical Southeast 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 San Antonio in spring?: In spring, tree pollen leads in San Antonio — trees pollinate Dec–Mar, ahead of grass (Mar–Aug). 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 San Antonio's pollen season distinctive?: San Antonio 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 San Antonio?: Through San Antonio's peak windows (tree Dec–Mar, grass Mar–Aug, 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.
When does the next pollen season start in San Antonio?: Tree pollen is next in San Antonio: it opens around week 49 (early December), peaks around week 2, and runs about 122 days.
What is the allergy forecast in San Antonio today?: With no live reading for San Antonio today, its allergy forecast is the seasonal estimate above: a typical September level of High, led by ragweed pollen.