Hartford Air Quality in Summer
Across 2019–2025, Hartford's summer (June–August) air quality had a median AQI of 51 (Moderate) over 644 monitored days in the Hartford-West Hartford-East Hartford, CT area. 8.2% of summer days (53 of 644) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 61.5% of days. The cleanest summer on record here was 2020 (median AQI 51, 2 days above 100) and the worst was 2021 (median 51, 14 days above 100, peak AQI 151).
- Good: 49.2%
- Moderate: 42.5%
- Unhealthy for Sensitive Groups: 7.0%
- Unhealthy or worse: 1.2%
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How is the air in Hartford in summer?
Moderate on a typical day: median AQI 51 across 2019–2025, with 8.2% of summer days above AQI 100. Ground-level ozone is the main driver.
- ✓49.2% of summer days were Good (AQI 0–50), 42.5% Moderate (51–100).
- ✓53 days of 644 reached AQI 101+; the summer peak was 185.
- ✓Cleanest month: August; worst month: June.
Frequently asked questions
What is the air quality like in Hartford in summer?▾
Across 2019–2025, the median daily AQI in Hartford in summer was 51 (Moderate). 49.2% of days were Good, 42.5% Moderate, and 8.2% reached Unhealthy for Sensitive Groups or worse, based on 644 monitored days in EPA's Air Quality System.
Is summer a good time for outdoor exercise in Hartford?▾
A typical summer day in Hartford is Moderate (median AQI 51): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 12 of summer days (8.2%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Hartford's summer air quality problems?▾
Ground-level ozone set the daily AQI on 61.5% of summer days in Hartford. The highest summer AQI recorded in 2019–2025 was 185 (Unhealthy), in 2021.
Hartford summer air quality, year by year
Hartford summer 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 |
|---|---|---|---|---|---|
| 2019 | 92 | 50 | 6 | 154 | O3 |
| 2020cleanest | 92 | 51 | 2 | 129 | O3 |
| 2021worst | 92 | 51 | 14 | 151 | O3 |
| 2022 | 92 | 47 | 7 | 147 | O3 |
| 2023 | 92 | 52 | 7 | 166 | O3 |
| 2024 | 92 | 50 | 8 | 185 | O3 |
| 2025 | 92 | 59 | 9 | 164 | O3 |
What summer air means in Hartford
A typical summer day in Hartford is Moderate (median AQI 51): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 12 of summer days (8.2%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Summer's median AQI of 51 is above Hartford's whole-year median of 43, making it one of the area's dirtier periods. Nationally, the median Summer AQI across every EPA metro area (308,645 metro-days, 2019–2025) is 46, so Hartford runs above the national Summer norm; 8.2% of its Summer days topped AQI 100 versus 3.6% nationally (above average).
Within the season, August is the cleanest month (median AQI 48, 5.1% of days above 100) and June the worst (median 50, 10.5% 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.