Fall Air Quality Patterns
Fall brings improving air quality as temperatures cool and ozone season ends, but extended wildfire season in the West can impact large regions. September through November offers generally favorable conditions.
Month-by-Month Fall Patterns
September: Extended Summer
Typical AQI: 50-80
Still warm in most regions. Wildfire season often peaks in West. Ozone declining but still present on hot days. Gradual improvement throughout month.
Regional Impacts
West Coast worst month for smoke. Southwest cooling rapidly. Northeast excellent conditions. Southeast improving as humidity drops.
October: Peak Fall Quality
Typical AQI: 35-55
Best air quality month for most regions. Ozone season over. Wildfires declining. Cool comfortable temperatures. Ideal outdoor conditions nationwide.
Excellent Everywhere
Even historically poor air quality cities improve dramatically. Perfect for outdoor activities, travel, and planning events. Rare AQI alerts.
November: Early Winter Signs
Typical AQI: 40-65
Still good quality overall. Wood smoke begins in mountain valleys. Heating season starts affecting some regions. First winter inversions possible.
Transition Month
Most areas remain excellent. Watch for early wood smoke in mountain communities. Cold snaps can trap pollution in valleys.
Regional Fall Patterns
Pacific Northwest
Mountain West
Northeast
Southeast
Fall Activity Guide
Ideal Fall Activities
- • Marathon training and races - best season for endurance sports
- • Hiking and camping - excellent visibility and air quality
- • Outdoor festivals and events - minimal air quality concerns
- • Open windows for natural ventilation - fresh air season
- • Photography - clear skies, excellent visibility for landscapes
- • Cycling tours - comfortable temps, clean air
- • Outdoor dining - pleasant conditions through November
- • School outdoor activities - safest season for recess