Niwot, Colorado Air Quality
Niwot has a median AQI of 50, earning an air quality grade of B+ — good air quality that ranks better than 13% of US cities. Air quality has been trending worse over the past decade, a concern for local residents and health officials. Ground-level ozone is the primary concern, typically peaking on warm sunny days due to vehicle and industrial emissions. In 2025, Niwot recorded 139 good air quality days (51% of monitored days) and 3 unhealthy days.
Population: 3,447 • County: Boulder
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Quick Facts
| Current AQI | 25 — Good |
| Air Quality Grade | B+ |
| Median AQI (2025) | 50 |
| vs. U.S. Cities | Better than 13% |
| Primary Pollutant | Ozone |
| Unhealthy Days/Year | 3 |
| 10-Year Trend | ↓ Worsening |
| Data Source | EPA AirNow |
Health Recommendation
Air quality is satisfactory, and air pollution poses little or no risk.
It's a great day to be active outside!
5-Day AQI Forecast
Last 30 Days
Current Pollutant Levels
Real-time data from EPA AirNow
AQI Trend (10 Years)
Air Quality Days by Year
2025 Air Quality Summary
Primary Pollutant Days (2025)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About Niwot Air Quality
What is the air quality in Niwot today?
The current AQI in Niwot is 25, which is rated "Good". Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in Niwot getting better or worse?
Air quality in Niwot has been worsening in recent years. The median AQI rose from 39 in 2016 to 50 in 2025.
What is the most common air pollutant in Niwot?
Ozone is the primary air pollutant in Niwot, responsible for the most air quality-impacted days in 2025. Ground-level ozone forms when sunlight reacts with vehicle and industrial emissions on warm days.
How many unhealthy air days does Niwot have per year?
In 2025, Niwot had 3 days when air quality was unhealthy or unhealthy for sensitive groups (AQI above 100). There were 139 good days and 131 moderate days out of 273 days monitored.
What air quality grade does Niwot receive?
Niwot receives an air quality grade of B+, placing it better than 13% of US cities. This grade is based on a median AQI of 50 for 2025, derived from EPA monitoring data.
Air Quality Grade
Better than 13% of US cities
Nearby Cities
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National Rankings
See how Niwot compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Niwot
Based on your area's air quality (median AQI: 50), we recommend these air purifiers to help protect your health indoors.
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Molekule Air Pro
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Honeywell HPA300
Powerful workhorse for large rooms. Built to last.
Blueair Blue Pure 211+
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