Forsyth, Montana Air Quality
Forsyth has a median AQI of 4, earning an air quality grade of A+ — excellent air quality that ranks better than 100% of US cities. Air quality has been improving steadily over the past decade, a positive sign for residents. Particulate matter (PM2.5) is the primary concern, often linked to vehicle traffic, industrial activity, and wildfire smoke. In 2025, Forsyth recorded 18 good air quality days (100% of monitored days).
Population: 1,728 • County: Rosebud
Current AQI
Quick Facts
| Current AQI | 20 — Good |
| Air Quality Grade | A+ |
| Median AQI (2025) | 4 |
| vs. U.S. Cities | Better than 100% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 0 |
| 10-Year Trend | ↑ Improving |
| Data Source | EPA AQS (historical) · AirNow (live) |
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 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for Forsyth is sourced from the Sheridan PD monitoring area, located approximately 101 miles from city center. This EPA-certified station continuously tracks particulate matter (PM2.5), the primary driver of air quality alerts in this area.
Forsyth typically sees its worst air quality during summer afternoons when heat and sunlight drive ground-level ozone formation from vehicle and industrial emissions. Morning readings are generally 15–25 points lower than afternoon peaks. Outdoor activity is best planned for early morning on high-ozone days.
AQI Trend (10 Years)
Air Quality Days by Year
Forsyth Median AQI by Year
Annual EPA air quality data for Forsyth — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 4 | 18 | — | 21 | PM2.5 |
| 2024 | 4 | 353 | — | 90 | NO₂ |
| 2023 | 3 | 279 | 1 | 132 | NO₂ |
| 2022 | 2 | 337 | — | 36 | NO₂ |
| 2021 | 38 | 266 | 14 | 155 | Ozone |
| 2020 | 37 | 321 | 5 | 154 | Ozone |
| 2019 | 36 | 328 | 1 | 108 | Ozone |
| 2018 | 38 | 302 | 2 | 133 | Ozone |
| 2017 | 39 | 277 | 11 | 196 | Ozone |
| 2016 | 38 | 307 | 1 | 132 | Ozone |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
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 Forsyth Air Quality
What is the air quality in Forsyth today?
The current AQI in Forsyth is 20, rated "Good". Air quality is good — outdoor activity is safe for everyone today. Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in Forsyth getting better or worse?
Air quality in Forsyth has been improving. The median AQI has dropped 34 points (from 38 in 2016 to 4 in 2025), a positive trend for residents.
What is the most common air pollutant in Forsyth?
PM2.5 is the primary air pollutant in Forsyth, responsible for 18 days (100% of monitored days) in 2025. Particulate matter originates from vehicle exhaust, wildfires, construction, and industrial activity.
How many unhealthy air days does Forsyth have per year?
In 2025, Forsyth recorded 100% good air quality days (18 days) out of 18 monitored days. There were 0 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 21.
What air quality grade does Forsyth receive?
Forsyth receives an air quality grade of A+, placing it better than 100% of US cities. This is based on a median AQI of 4 in 2025, with 18 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 100% of US cities
Nearby Cities
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National Rankings
See how Forsyth compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Forsyth
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