When is pollen worst in Honolulu?

There's barely an off-switch for grass in Honolulu — it pollinates year-round, so the usual "three waves" calendar flattens into a near-constant grass baseline. Tree pollen still spikes Dec–Mar and ragweed adds a Sep–Nov layer on top. Currently, grass and ragweed pollen are in season.

What's in the air in Honolulu right now?

In September, grass and ragweed pollen are in season in Honolulu — grass peaks year-round and ragweed peaks Sep–Nov. On Honolulu's warm tropical / sub-tropical calendar the typical September level is Moderate, led by grass pollen — a seasonal estimate, not a live count.

Is tree or grass pollen higher in Honolulu in spring?

In Honolulu, the tree-versus-grass question is unusual: trees do peak Dec–Mar, but grass never really yields (year-round), so on most spring days BOTH are airborne. A spring bad day here is more often grass than tree, the reverse of colder regions.

What makes Honolulu's pollen season distinctive?

Honolulu sits in the warm tropical / sub-tropical zone, which means almost no off-season for grass, which pollinates year-round here, so the calendar is less about timing and more about the constant grass baseline. That shapes when symptoms hit and which allergen to watch.

How do I reduce pollen exposure in Honolulu?

Through Honolulu's peak windows (tree Dec–Mar, grass year-round, ragweed Sep–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 Honolulu?

Tree pollen is next in Honolulu: it opens around week 49 (early December), peaks around week 7, and runs about 122 days.

What is the allergy forecast in Honolulu today?

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

Honolulu, Hawaii Pollen Count & Allergy Forecast

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

Honolulu, HI · Pollen season

In September, grass and ragweed pollen are in season in Honolulu — grass peaks year-round and ragweed peaks Sep–Nov.

Based on the seasonal pollen calendar for this region.

Honolulu on the WeatherStory Allergy Index

Honolulu isn't one of the 100 metros on the WeatherStory Allergy Index, but the nearest ranked metro — San Francisco, CA, about 2391 miles away — sits at #42 with a 274-day combined pollen season.

#42of 100nearest ranked metro

Load index: 34
Combined season: 274 days
Heaviest load: Tree · 122 days
Nearest ranked metro: San Francisco, CA · ~2391 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

Grass pollen typically leads in Honolulu in September, at an estimated Moderate level.

Pollen by type this season

TreeOut of seasonpeaks Dec–Mar
GrassIn seasonpeaks year-round
Weed / RagweedIn seasonpeaks Sep–Nov

What pollinates near Honolulu

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

Trees

Oak Quercuspeaks January–March
Australian pine Casuarinapeaks January–March
Bayberry Myrica ceriferapeaks January–March
Palm Arecaceaepeaks March–May
Melaleuca Melaleuca quinquenerviapeaks October–December

Grasses

Bahia grass Paspalum notatumpeaks April–October
Bermuda grass Cynodon dactylonpeaks March–November
St. Augustine grass Stenotaphrum secundatumpeaks April–October
Johnson grass Sorghum halepensepeaks May–September

Weeds

Ragweed Ambrosiapeaks September–November
Pigweed Amaranthuspeaks September–November
Sedge Cyperuspeaks May–October
Dog fennel Eupatorium capillifoliumpeaks September–November

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

Honolulu’s allergy year

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

JFMAMJJASOND

TreeDec–Mar

Grassyear-round

RagweedSep–Nov

How Honolulu compares to the U.S. average

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

Tree~11 wks earlier

Grass~20 wks earlier

Ragweed~4 wks later

“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 Honolulu’s pollen count works

The calendar above is tuned to Honolulu’s warm tropical / sub-tropical climate, not a national average: tree pollen runs from week 49 (early December) to week 13 (late March), grass from week 1 (early January) to week 52 (late December), and ragweed from week 36 (early September) to week 48 (late November) here — a 365-day combined pollen season. Those windows are why grass and ragweed pollen are in season in Honolulu right now.

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

For the science behind Honolulu’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 Honolulu?: There's barely an off-switch for grass in Honolulu — it pollinates year-round, so the usual "three waves" calendar flattens into a near-constant grass baseline. Tree pollen still spikes Dec–Mar and ragweed adds a Sep–Nov layer on top. Currently, grass and ragweed pollen are in season.
What's in the air in Honolulu right now?: In September, grass and ragweed pollen are in season in Honolulu — grass peaks year-round and ragweed peaks Sep–Nov. On Honolulu's warm tropical / sub-tropical calendar the typical September level is Moderate, led by grass pollen — a seasonal estimate, not a live count.
Is tree or grass pollen higher in Honolulu in spring?: In Honolulu, the tree-versus-grass question is unusual: trees do peak Dec–Mar, but grass never really yields (year-round), so on most spring days BOTH are airborne. A spring bad day here is more often grass than tree, the reverse of colder regions.
What makes Honolulu's pollen season distinctive?: Honolulu sits in the warm tropical / sub-tropical zone, which means almost no off-season for grass, which pollinates year-round here, so the calendar is less about timing and more about the constant grass baseline. That shapes when symptoms hit and which allergen to watch.
How do I reduce pollen exposure in Honolulu?: Through Honolulu's peak windows (tree Dec–Mar, grass year-round, ragweed Sep–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 Honolulu?: Tree pollen is next in Honolulu: it opens around week 49 (early December), peaks around week 7, and runs about 122 days.
What is the allergy forecast in Honolulu today?: With no live reading for Honolulu today, its allergy forecast is the seasonal estimate above: a typical September level of Moderate, led by grass pollen.