When is pollen worst in Sun Valley?

Sun Valley runs the classic three-wave calendar: tree pollen Apr–Jun, grass Jun–Aug, 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 Sun Valley right now?

In September, ragweed pollen is in season in Sun Valley, peaking Aug–Oct. On Sun Valley's high-elevation Mountain West 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 Sun Valley in spring?

In spring, tree pollen leads in Sun Valley — trees pollinate Apr–Jun, ahead of grass (Jun–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 Sun Valley's pollen season distinctive?

Sun Valley sits in the high-elevation Mountain West zone, which means short, sharp seasons set late by elevation, with sagebrush adding to the late-summer weed load. That shapes when symptoms hit and which allergen to watch.

How do I reduce pollen exposure in Sun Valley?

Through Sun Valley's peak windows (tree Apr–Jun, grass Jun–Aug, 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 Sun Valley?

Tree pollen is next in Sun Valley: it opens around week 14 (early April), peaks around week 20, and runs about 91 days.

What is the allergy forecast in Sun Valley today?

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

Sun Valley, Idaho Pollen Count & Allergy Forecast

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

Sun Valley, ID · Pollen season

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

Based on the seasonal pollen calendar for this region.

Sun Valley on the WeatherStory Allergy Index

Sun Valley isn't one of the 100 metros on the WeatherStory Allergy Index, but the nearest ranked metro — Boise, ID, about 95 miles away — sits at #100 with a 213-day combined pollen season.

#100of 100nearest ranked metro

Load index: 21
Combined season: 213 days
Heaviest load: Ragweed · 91 days
Nearest ranked metro: Boise, ID · ~95 mi

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 Sun Valley in September, at an estimated High level.

Pollen by type this season

TreeOut of seasonpeaks Apr–Jun
GrassOut of seasonpeaks Jun–Aug
Weed / RagweedIn seasonpeaks Aug–Oct

What pollinates near Sun Valley

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

Trees

Juniper Juniperuspeaks March–April
Cottonwood Populuspeaks March–April
Aspen Populus tremuloidespeaks April–May
Ponderosa pine Pinus ponderosapeaks May–June
Box elder Acer negundopeaks March–April

Grasses

Kentucky bluegrass Poa pratensispeaks May–July
Smooth brome Bromus inermispeaks May–July
Timothy Phleum pratensepeaks June–July
Orchard grass Dactylis glomeratapeaks June–July

Weeds

Sagebrush Artemisia tridentatapeaks August–September
Common ragweed Ambrosia artemisiifoliapeaks August–September
Russian thistle Salsola traguspeaks August–September
Kochia Bassia scopariapeaks August–September

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

Sun Valley’s allergy year

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

JFMAMJJASOND

TreeApr–Jun

GrassJun–Aug

RagweedAug–Oct

How Sun Valley compares to the U.S. average

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

Tree~2 wks later

Grass~2 wks later

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 Sun Valley’s pollen count works

The calendar above is tuned to Sun Valley’s high-elevation Mountain West climate, not a national average: tree pollen runs from week 14 (early April) to week 26 (late June), grass from week 23 (early June) to week 35 (late August), and ragweed from week 31 (early August) to week 43 (late October) here — a 213-day combined pollen season. Those windows are why ragweed pollen is the one in season in Sun Valley right now.

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

For the science behind Sun Valley’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 Sun Valley?: Sun Valley runs the classic three-wave calendar: tree pollen Apr–Jun, grass Jun–Aug, 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 Sun Valley right now?: In September, ragweed pollen is in season in Sun Valley, peaking Aug–Oct. On Sun Valley's high-elevation Mountain West 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 Sun Valley in spring?: In spring, tree pollen leads in Sun Valley — trees pollinate Apr–Jun, ahead of grass (Jun–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 Sun Valley's pollen season distinctive?: Sun Valley sits in the high-elevation Mountain West zone, which means short, sharp seasons set late by elevation, with sagebrush adding to the late-summer weed load. That shapes when symptoms hit and which allergen to watch.
How do I reduce pollen exposure in Sun Valley?: Through Sun Valley's peak windows (tree Apr–Jun, grass Jun–Aug, 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 Sun Valley?: Tree pollen is next in Sun Valley: it opens around week 14 (early April), peaks around week 20, and runs about 91 days.
What is the allergy forecast in Sun Valley today?: With no live reading for Sun Valley today, its allergy forecast is the seasonal estimate above: a typical September level of High, led by ragweed pollen.