Pollen Today for Hesperia, CA
Mild weed pollen in Hesperia, CA today
Tree: Low · Grass: Low · Weed: Moderate
Tree pollenLow (UPI 0/5)
UPI is the Universal Pollen Index, a 0–5 scale (0 none, 5 very high) that is comparable across pollen types and locations.
- Grass pollenLow (UPI 1/5)
- Weed pollenModerate (UPI 3/5)
- TimingCounts peak 10am–3pm; lowest overnight and after rain
- TipMorning hours tend to be higher
Data as of Oct 18, 2026
Coming Up
What’s in the air in Hesperia right now
The pollen model for Hesperia currently tracks 2 active species — Ragweed (UPI 3/5), Grasses (UPI 1/5). Ragweed is the strongest source right now.
Looking at the 5-day forecast, weed pollen is expected to ease, with Tuesday looking like the lowest day.
Ragweed is a weed pollen source. A single ragweed plant can release about a billion pollen grains, and it dominates the late-summer-to-first-frost allergy season across most of the US.
Grasses is a grass pollen source. Grass is the most widespread pollen allergen in the country, typically peaking from late spring through midsummer — and lawn mowing stirs it up even outside the peak.
The tree, grass, and weed rows above roll these species into three groups, but knowing the exact species helps: if allergy testing showed what you react to, you can check whether your trigger is actually the one flying today.
Ragweed is the driver this time of year, and in Hesperia it has roughly 44 days left to run. Weed pollen doesn't stop on a calendar date — it stops when a hard frost kills the plants, and Hesperia's average first frost falls around December 1.
That is why the same ragweed season is weeks shorter in the northern states than in the South: identical plants, different frost dates. A single ragweed plant can release around a billion pollen grains, and they travel hundreds of miles on the wind, so a low local count doesn't guarantee a quiet day.
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