What Is the Air Quality in Fergus, Montana?

Fergus, Montana earns a C — air quality is fair, but not great. With a 5-year median AQI of 40, the city sees a meaningful number of "Moderate" days each year, when the EPA flags air as a concern for unusually sensitive people.

Fergus, Montana's 5-year median AQI of 40 is right around the national average of 41 across the 1,020 monitored U.S. cities tracked here. Within Montana, Fergus, Montana runs more polluted than the state average of 31 — local sources or geography are concentrating pollution above the state's typical reading.

For context within Montana: Rosebud, Montana currently holds the state's cleanest grade (A, AQI 23), while Sanders, Montana sits at the bottom (D, AQI 36).

Air quality in Fergus, Montana has been getting worse over the past decade, with median AQI climbing by roughly 0.4 points per year. That bucks the national trend of broad improvement, and most often reflects either growing wildfire smoke exposure (particularly across the West) or rising local emissions from population and freight growth.

In 2014, Fergus, Montana posted a median AQI of 37. By 2023 that figure was 41 — a rise of 4 AQI points dirtier across 10 years of EPA records.

Across the past five years, this area has logged 26 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 5 days per year. That is roughly typical for a U.S. metro, with most caution days clustered in summer (ozone) or wildfire season.

Healthy adults can continue normal outdoor activity in most weather, but should pay attention to AQI alerts during the worst pollution windows. People with asthma, heart disease, or pregnancy should reduce prolonged or intense outdoor exertion on flagged days, and consider running an indoor HEPA air cleaner during peak season. Because ozone peaks in the afternoon on hot sunny days, plan outdoor exercise for early morning or after sunset on bad-air days.