Portland, OR Air Quality in April
Across 2019–2025, Portland's April air quality had a median AQI of 38 (Good) over 210 monitored days in the Portland-Vancouver-Hillsboro, OR-WA area. 0.0% of April days (0 of 210) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 71.4% of days. The cleanest April on record here was 2019 (median AQI 37, 0 days above 100) and the worst was 2021 (median 43, 0 days above 100, peak AQI 58).
- Good: 90.5%
- Moderate: 9.5%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
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How is the air in Portland in April?
Good on a typical day: median AQI 38 across 2019–2025, with 0.0% of April days above AQI 100. Ground-level ozone is the main driver.
- ✓90.5% of April days were Good (AQI 0–50), 9.5% Moderate (51–100).
- ✓0 days of 210 reached AQI 101+; the April peak was 71.
- ✓Best April: 2019; worst April: 2021.
Frequently asked questions
What is the air quality like in Portland in April?▾
Across 2019–2025, the median daily AQI in Portland in April was 38 (Good). 90.5% of days were Good, 9.5% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 210 monitored days in EPA's Air Quality System.
Is April a good time for outdoor exercise in Portland?▾
A typical April day in Portland sits in the Good range (median AQI 38), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of April days reached AQI 101+ in 2019–2025.
Which pollutant causes Portland's April air quality problems?▾
Ground-level ozone set the daily AQI on 71.4% of April days in Portland. The highest April AQI recorded in 2019–2025 was 71 (Moderate), in 2021.
Portland April air quality, year by year
Portland April air quality by year (Portland-Vancouver-Hillsboro, OR-WA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 30 | 37 | 0 | 51 | O3 |
| 2020 | 30 | 38 | 0 | 71 | O3 |
| 2021worst | 30 | 43 | 0 | 58 | O3 |
| 2022 | 30 | 37 | 0 | 54 | O3 |
| 2023 | 30 | 37 | 0 | 62 | O3 |
| 2024 | 30 | 38 | 0 | 51 | O3 |
| 2025 | 30 | 39 | 0 | 51 | O3 |
What April air means in Portland
A typical April day in Portland sits in the Good range (median AQI 38), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of April days reached AQI 101+ in 2019–2025.
April's median AQI of 38 is in line with Portland's whole-year median of 41, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median April AQI across every EPA metro area (100,677 metro-days, 2019–2025) is 44, so Portland runs below the national April norm; 0.0% of its April days topped AQI 100 versus 0.7% nationally (about the same).
April is part of Portland's spring season (March, April, May); the spring page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Portland
The latest EPA AirNow observation puts Portland's AQI at 29 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current Portland air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Portland-Vancouver-Hillsboro, OR-WA), 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.