Best Time to Visit US Cities by Air Quality
Air quality varies dramatically by season and location. Plan your travels around the best air quality months to maximize outdoor activities, protect sensitive individuals, and enjoy cleaner, healthier city experiences.
Quick Reference: Best Months by Region
| Region | Best Months | Avoid Months | Primary Concern |
|---|---|---|---|
| Pacific Northwest | April-June, September-October | July-August | Wildfire smoke |
| California | November-April | June-September | Wildfires + ozone |
| Southwest | October-April | June-August | Heat + ozone |
| Mountain West | May-October | December-February | Winter inversions |
| Texas | October-April | June-August | Heat + ozone |
| Southeast | September-May | June-July | Ozone + humidity |
| Northeast | April-June, September-October | July-August | Summer ozone |
| Midwest | April-June, September-October | July-August | Ozone + heat |
Major Cities: Month-by-Month Air Quality
West Coast Cities
Los Angeles
Winter months have lowest ozone. Summer brings daily air quality alerts. Marine layer helps but heat drives ozone formation June-September.
San Francisco
Excellent air quality most of year. Wildfire smoke from Sierras impacts late summer. Fog keeps temperatures cool year-round, limiting ozone formation.
Seattle
Clean air most of year thanks to marine influence. Wildfire season brings worst air quality. August smoke events can be severe. Spring and fall ideal.
Portland
Similar to Seattle with wildfire vulnerability. September 2020 had hazardous smoke for weeks. Spring especially beautiful with excellent air quality.
Mountain West Cities
Salt Lake City
Winter inversions create worst air in nation. January can see 2+ week pollution traps. March through November typically excellent. Avoid mid-winter visits.
Denver
Brown cloud during winter inversions. Summer wildfire smoke possible but less severe than Utah. Spring and fall ideal with 300+ days of sunshine annually.
Phoenix
Extreme heat drives ozone formation in summer. Winter and spring excellent for outdoor activities. Dust storms possible March-September but air quality generally good.
Las Vegas
Similar to Phoenix with summer ozone concerns. California wildfire smoke can reach valley. Winter months ideal with pleasant temperatures and clean air.
Texas Cities
Houston
Industrial emissions + heat + humidity = summer ozone issues. Winter through spring excellent. Gulf breezes help but summer heat overwhelms. October particularly nice.
Dallas-Fort Worth
Consistent ozone issues during summer heat. Urban sprawl contributes to vehicle emissions. Spring wildflower season (March-April) combines beauty with good air quality.
Austin
Better than Houston/Dallas but still summer ozone concerns. Hill Country location helps. SXSW in March coincides with excellent air quality. October music festivals also ideal timing.
San Antonio
Similar pattern to other Texas cities. Winter months ideal for Riverwalk tourism. Summer heat drives ozone. Fiesta in April enjoys good air quality.
Northeast Cities
New York City
Summer heat waves bring ozone alerts. Canadian wildfire smoke reached hazardous levels June 2023. Spring and fall ideal for sightseeing. Winter acceptable but cold.
Boston
Similar to NYC with summer ozone concerns. Coastal location provides some relief. Fall foliage season (October) combines beautiful scenery with excellent air quality.
Philadelphia
Summer humidity and heat create ozone. Spring and fall ideal for historical tours. Winter acceptable with occasional cold snaps. Canadian smoke events possible in summer.
Washington DC
Cherry blossom season (late March-early April) features excellent air quality. Summer humidity + heat = ozone alerts. Fall colors with good air in October.
Midwest Cities
Chicago
Lake Michigan moderates but summer still brings ozone days. Canadian wildfire smoke impacts possible. Winters very cold. Spring and fall ideal weather + air quality window.
Minneapolis
Generally excellent air quality. Summer occasionally sees ozone alerts but less severe than other cities. Canadian wildfire smoke possible. Winters brutally cold but air clean.
Detroit
Industrial past but air quality much improved. Summer heat brings occasional ozone. Spring and fall ideal. Canadian smoke events possible in summer months.
St. Louis
Mississippi River humidity + summer heat = ozone concerns. Gateway Arch visits best in spring or fall. Winter acceptable but variable weather. Spring months ideal.
Air Quality Travel Planning Tips
Before Booking
- •Check historical AQI data for your destination and travel dates
- •Consider shoulder seasons (spring/fall) for most US cities
- •Avoid wildfire season in Western states (July-September)
- •Check if destination has winter inversion issues
- •Book hotels with air filtration for sensitive travelers
During Your Trip
- •Check daily AQI forecasts each morning
- •Schedule outdoor activities for morning hours when ozone is lowest
- •Have indoor backup plans for high pollution days
- •Carry N95 masks for unexpected smoke or pollution events
- •Use apps to track real-time AQI at your location
Special Travel Considerations
Families with Children
- • Children more vulnerable to air pollution
- • Choose spring or fall for outdoor activities
- • Avoid peak summer ozone season
- • Plan indoor attractions for poor air days
- • Check school calendar - locals may have insight
Respiratory Conditions
- • Strictly avoid high-risk seasons
- • Bring all medications and rescue inhalers
- • Book accommodations with HEPA filtration
- • Have travel insurance for weather-related changes
- • Consider trip cancellation if air quality deteriorates
Active Travelers
- • Hiking/biking trips require excellent air quality
- • Research seasonal patterns carefully
- • Have backup dates or locations
- • Morning activities reduce ozone exposure
- • Monitor forecasts week before departure