Hartford Air Quality in Fall
Across 2019–2025, Hartford's fall (September–November) air quality had a median AQI of 37 (Good) over 637 monitored days in the Hartford-West Hartford-East Hartford, CT area. 0.3% of fall days (2 of 637) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 55.3% of days. The cleanest fall on record here was 2024 (median AQI 33, 0 days above 100) and the worst was 2019 (median 34, 2 days above 100, peak AQI 122).
- Good: 80.1%
- Moderate: 19.6%
- Unhealthy for Sensitive Groups: 0.3%
- Unhealthy or worse: 0.0%
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How is the air in Hartford in fall?
Good on a typical day: median AQI 37 across 2019–2025, with 0.3% of fall days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓80.1% of fall days were Good (AQI 0–50), 19.6% Moderate (51–100).
- ✓2 days of 637 reached AQI 101+; the fall peak was 122.
- ✓Cleanest month: October; worst month: September.
Frequently asked questions
What is the air quality like in Hartford in fall?▾
Across 2019–2025, the median daily AQI in Hartford in fall was 37 (Good). 80.1% of days were Good, 19.6% Moderate, and 0.3% reached Unhealthy for Sensitive Groups or worse, based on 637 monitored days in EPA's Air Quality System.
Is fall a good time for outdoor exercise in Hartford?▾
A typical fall day in Hartford sits in the Good range (median AQI 37), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of fall days reached AQI 101+ in 2019–2025.
Which pollutant causes Hartford's fall air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 55.3% of fall days in Hartford. The highest fall AQI recorded in 2019–2025 was 122 (Unhealthy for Sensitive Groups), in 2019.
Hartford fall air quality, year by year
Hartford fall air quality by year (Hartford-West Hartford-East Hartford, CT, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019worst | 91 | 34 | 2 | 122 | PM2.5 |
| 2020 | 91 | 38 | 0 | 98 | PM2.5 |
| 2021 | 91 | 40 | 0 | 74 | PM2.5 |
| 2022 | 91 | 37 | 0 | 87 | PM2.5 |
| 2023 | 91 | 37 | 0 | 98 | PM2.5 |
| 2024cleanest | 91 | 33 | 0 | 93 | O3 |
| 2025 | 91 | 36 | 0 | 80 | O3 |
What fall air means in Hartford
A typical fall day in Hartford sits in the Good range (median AQI 37), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of fall days reached AQI 101+ in 2019–2025.
Fall's median AQI of 37 is below Hartford's whole-year median of 43, making it one of the area's cleaner periods. Nationally, the median Fall AQI across every EPA metro area (296,275 metro-days, 2019–2025) is 40, so Hartford runs in line with the national Fall norm; 0.3% of its Fall days topped AQI 100 versus 1.5% nationally (below average).
Within the season, October is the cleanest month (median AQI 34, 0.0% of days above 100) and September the worst (median 37, 1.0% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Hartford
The latest EPA AirNow observation puts Hartford's AQI at 36 (PM2.5). The figures above are multi-year season statistics, not today's reading.
View current Hartford air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Hartford-West Hartford-East Hartford, CT), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.