Houston Air Quality in May
Across 2019–2025, Houston's May air quality had a median AQI of 64 (Moderate) over 217 monitored days in the Houston-The Woodlands-Sugar Land, TX area. 16.6% of May days (36 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 54.8% of days. The cleanest May on record here was 2021 (median AQI 56, 1 day above 100) and the worst was 2023 (median 80, 12 days above 100, peak AQI 205).
- Good: 5.1%
- Moderate: 78.3%
- Unhealthy for Sensitive Groups: 12.9%
- Unhealthy or worse: 3.7%
Extra Protection for Houston Homes
Air quality in Houston is moderate (AQI 57), with fine particles (PM2.5) the main concern. A True-HEPA purifier gives sensitive groups — kids, seniors and anyone with asthma or allergies — cleaner air indoors on days like today.
Recommended: Coway AP-1512HH Mighty — True HEPA + carbon · CADR ~246 CFM · rooms up to 361 sq ft
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How is the air in Houston in May?
Moderate on a typical day: median AQI 64 across 2019–2025, with 16.6% of May days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓5.1% of May days were Good (AQI 0–50), 78.3% Moderate (51–100).
- ✓36 days of 217 reached AQI 101+; the May peak was 205.
- ✓Best May: 2021; worst May: 2023.
Frequently asked questions
What is the air quality like in Houston in May?▾
Across 2019–2025, the median daily AQI in Houston in May was 64 (Moderate). 5.1% of days were Good, 78.3% Moderate, and 16.6% 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 Houston?▾
A typical May day in Houston is Moderate (median AQI 64): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 6 of May days (16.6%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Houston's May air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 54.8% of May days in Houston. The highest May AQI recorded in 2019–2025 was 205 (Very Unhealthy), in 2023.
Houston May air quality, year by year
Houston May air quality by year (Houston-The Woodlands-Sugar Land, TX, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 62 | 2 | 133 | PM2.5 |
| 2020 | 31 | 61 | 3 | 151 | O3 |
| 2021cleanest | 31 | 56 | 1 | 161 | PM2.5 |
| 2022 | 31 | 67 | 8 | 164 | PM2.5 |
| 2023worst | 31 | 80 | 12 | 205 | O3 |
| 2024 | 31 | 77 | 7 | 182 | PM2.5 |
| 2025 | 31 | 64 | 3 | 140 | PM2.5 |
What May air means in Houston
A typical May day in Houston is Moderate (median AQI 64): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 6 of May days (16.6%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
May's median AQI of 64 is in line with Houston's whole-year median of 61, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median May AQI across every EPA metro area (104,064 metro-days, 2019–2025) is 44, so Houston runs above the national May norm; 16.6% of its May days topped AQI 100 versus 1.3% nationally (above average).
May is part of Houston's spring season (March, April, May); the spring page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Houston
The latest EPA AirNow observation puts Houston's AQI at 57 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current Houston air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Houston-The Woodlands-Sugar Land, TX), 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.