Boise Air Quality in May
Across 2019–2025, Boise's May air quality had a median AQI of 46 (Good) over 217 monitored days in the Boise City, ID area. 0.5% of May days (1 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 82.0% of days. The cleanest May on record here was 2022 (median AQI 42, 0 days above 100) and the worst was 2023 (median 49, 1 day above 100, peak AQI 101).
- Good: 71.0%
- Moderate: 28.6%
- Unhealthy for Sensitive Groups: 0.5%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Boise
Today's main pollutant in Boise is ground-level ozone (AQI 38). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
As an Amazon Associate, we earn from qualifying purchases.
How is the air in Boise in May?
Good on a typical day: median AQI 46 across 2019–2025, with 0.5% of May days above AQI 100. Ground-level ozone is the main driver.
- ✓71.0% of May days were Good (AQI 0–50), 28.6% Moderate (51–100).
- ✓1 day of 217 reached AQI 101+; the May peak was 101.
- ✓Best May: 2022; worst May: 2023.
Frequently asked questions
What is the air quality like in Boise in May?▾
Across 2019–2025, the median daily AQI in Boise in May was 46 (Good). 71.0% of days were Good, 28.6% Moderate, and 0.5% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is May a good time for outdoor exercise in Boise?▾
A typical May day in Boise sits in the Good range (median AQI 46), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of May days reached AQI 101+ in 2019–2025.
Which pollutant causes Boise's May air quality problems?▾
Ground-level ozone set the daily AQI on 82.0% of May days in Boise. The highest May AQI recorded in 2019–2025 was 101 (Unhealthy for Sensitive Groups), in 2023.
Boise May air quality, year by year
Boise May air quality by year (Boise City, ID, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 44 | 0 | 58 | PM2.5 |
| 2020 | 31 | 44 | 0 | 64 | O3 |
| 2021 | 31 | 44 | 0 | 69 | O3 |
| 2022cleanest | 31 | 42 | 0 | 54 | O3 |
| 2023worst | 31 | 49 | 1 | 101 | O3 |
| 2024 | 31 | 48 | 0 | 76 | O3 |
| 2025 | 31 | 61 | 0 | 97 | O3 |
What May air means in Boise
A typical May day in Boise sits in the Good range (median AQI 46), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of May days reached AQI 101+ in 2019–2025.
May's median AQI of 46 is below Boise's whole-year median of 54, making it one of the area's cleaner periods. Nationally, the median May AQI across every EPA metro area (104,064 metro-days, 2019–2025) is 44, so Boise runs in line with the national May norm; 0.5% of its May days topped AQI 100 versus 1.3% nationally (about the same).
May is part of Boise's spring season (March, April, May); the spring page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Boise
The latest EPA AirNow observation puts Boise's AQI at 38 (O3). The figures above are multi-year month statistics, not today's reading.
View current Boise air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Boise City, ID), 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.