Pollen Today for San Tan Valley, AZ
Moderate pollen in San Tan Valley, AZ — Grass leading
Tree: Low · Grass: Moderate · 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 pollenModerate (UPI 3/5)
- 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
Next low-pollen day: Monday, Oct 19
What’s in the air in San Tan Valley right now
The pollen model for San Tan Valley currently tracks 2 active species — Grasses (UPI 3/5), Ragweed (UPI 3/5). Grasses is the strongest source right now.
Looking at the 5-day forecast, grass pollen is expected to ease, with Monday looking like the lowest day.
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.
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.
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 San Tan Valley it has roughly 54 days left to run. Weed pollen doesn't stop on a calendar date — it stops when a hard frost kills the plants, and San Tan Valley's average first frost falls around December 11.
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.
Worth having
Affiliate disclosure: we may earn a commission if you buy through these links, at no extra cost to you. We only list things we’d recommend anyway.