Allergy Season Calculator
Check expected tree, grass, and weed pollen by US region and month.
Returns peak dates, outdoor risk level, and prevention tips for hay fever sufferers.
Allergy season forecasting combines pollen count data with personal sensitivity levels to estimate symptom severity and medication timing. While pollen counts are measured by certified laboratories, you can estimate your personal allergy burden using severity scoring and calculate optimal antihistamine timing.
Pollen burden index formula: Allergy Burden = Pollen Count × Sensitivity Factor × Exposure Time (hours)
Where:
- Pollen Count — grains per cubic meter of air, reported daily by local monitoring stations
- Sensitivity Factor — personal multiplier: 1.0 (mild), 1.5 (moderate), 2.0 (severe)
- Exposure Time — hours spent outdoors during peak pollen hours
Pollen count severity scale (standard):
- Low: 0–9 grains/m³ — minimal symptoms even for sensitive individuals
- Moderate: 10–49 grains/m³ — noticeable symptoms in sensitive people
- High: 50–99 grains/m³ — significant symptoms; medication recommended
- Very High: 100–199 grains/m³ — severe symptoms; limit outdoor exposure
- Extreme: 200+ grains/m³ — dangerous; stay indoors if possible
Medication timing guide: Pre-dose Lead Time = 1–2 hours before outdoor activity (for antihistamines) Nasal corticosteroids (Flonase, Nasacort) require 2–4 weeks of daily use before reaching full effectiveness.
Peak pollen hours by type:
- Tree pollen: 5 AM – 10 AM (spring)
- Grass pollen: 11 AM – 3 PM (late spring/summer)
- Ragweed/weed pollen: 10 AM – 3 PM (late summer/fall)
Regional allergy seasons:
- Northeast US: Tree (Mar–May), Grass (May–Jul), Ragweed (Aug–Oct)
- Southeast US: Year-round — especially oak (Feb–Apr) and cedar (Dec–Feb)
- Pacific Northwest: Heavy tree pollen Mar–Jun
Symptom scoring (TNSS — Total Nasal Symptom Score): Rate each of 4 symptoms (runny nose, nasal congestion, sneezing, itching) on a 0–3 scale. Maximum score = 12 (most severe possible)
Worked example: Pollen count: 75 grains/m³ (high). Personal sensitivity: moderate (1.5). Outdoor exposure: 3 hours at peak time.
Allergy Burden = 75 × 1.5 × 3 = 337.5 burden units
Recommendation: Take non-drowsy antihistamine (cetirizine 10mg) 1–2 hours before going out; wear wraparound sunglasses to block pollen contact with eyes; shower and change clothing upon return.