Metro area air quality · 2025

Sioux City, IA-NE-SD

Median AQI 39 (Good). 80.8% of monitored days rated Good across this metro's EPA monitoring network.

39
Median AQI
80.8%
Good-air days
0
Unhealthy days
65%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 265 monitored days. EPA AQS →

The verdict

The Sioux City, IA-NE-SD metro runs good on the EPA scale, cleaner than the median US metro, a median AQI of 39 with 80.8% of 265 monitored days in the Good band.

39
median AQI · Good
80.8%
days rated Good
65%
cleaner than US metros
122
worst single reading

No day crossed into the Unhealthy tier across the metro's monitors in 2025.

Insights: Sioux City, IA-NE-SD metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 39 over 265 measured days in 2025, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 214 Good days (81%), 48 Moderate (18%), and 3 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 61 while the highest single-day reading hit 122 (USG). Metro residents averaged roughly 24.2 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -77 and the median AQI moved +0 points, which classifies the multi-year trajectory as stable. The metro avoided any Unhealthy-tier days entirely, an outcome that typically reflects favorable wind patterns, lower industrial density, or effective regional emission controls. Metros with comparable AQI profiles include Beaver Dam, WI (76.4% good, AQI 39); Bennington, VT (82.9% good, AQI 39); Billings, MT (86.7% good, AQI 39).

Air Quality Summary

Median AQI

39

Good

Good Days

80.8%

214 of 265 days

Max AQI

122

USG

Health Grade

Good

90th pct: 61

AQI Day Breakdown (2025)

Distribution of 265 monitored days across EPA AQI categories.

Good

214

81%

Moderate

48

18%

USG

3

1%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Sioux City, IA-NE-SD metro area's air quality is rated Good based on 80.8% good air days. No unhealthy air days were recorded in 2025.

Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.

How does the Sioux City, IA-NE-SD metro compare?

How Sioux City, IA-NE-SD compares

Good-day share better than US avg
Sioux City, IA-NE-SD 80.8%
Beaver Dam, WI 76.4%
US average 71.3%
Median AQI better than US avg
Sioux City, IA-NE-SD 39
Beaver Dam, WI 39
US average 41
Unhealthy days / yr better than US avg
Sioux City, IA-NE-SD 0
Beaver Dam, WI 0
US average 1

5-Year Air Quality Trend

Air quality is stable in the Sioux City, IA-NE-SD metro. Best year: 2020 (291 good days).

Year Good Moderate Unhealthy Median AQI
2020 291 74 0 39
2021 194 105 2 45
2022 91 22 0 36
2023 71 45 2 43
2024 224 60 0 43
2025 214 48 0 39

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Sioux City, IA-NE-SD.

Beaver Dam, WI

AQI 39 · 76.4% good

39

Bennington, VT

AQI 39 · 82.9% good

39

Billings, MT

AQI 39 · 86.7% good

39

Blacksburg-Christiansburg-Radford, VA

AQI 39 · 92.4% good

39

Brainerd, MN

AQI 39 · 84.4% good

39

Brunswick, GA

AQI 39 · 81.9% good

39

More Air Quality Data

Explore EPA air quality rankings and guides across U.S. metros and counties.

Cleanest Metro Areas

U.S. metros ranked by their share of Good air-quality days.

Worst Air Quality

Counties and metros with the most unhealthy air days.

All Metro Areas

Annual AQI by CBSA for every monitored U.S. metro area.

Best and Worst City Air

What drives urban air quality and how metro areas compare.

Air Quality Guides

Frequently Asked Questions

What is the air quality in the Sioux City, IA-NE-SD metro area? ▼
The Sioux City, IA-NE-SD metro area has a median Air Quality Index (AQI) of 39, rated "Good." 80.8% of monitored days (214 out of 265) had good air quality in 2025.
How many unhealthy air days does Sioux City, IA-NE-SD have? ▼
In 2025, the Sioux City, IA-NE-SD metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 122.
Is air quality in Sioux City, IA-NE-SD getting better or worse? ▼
Air quality in the Sioux City, IA-NE-SD metro is stable based on 5-year trends (2020-2025). Best year: 2020 with 291 good days. Worst year: 2023 with 71 good days.
What does AQI 39 mean for health? ▼
An AQI of 39 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
What is the 90th percentile AQI for Sioux City, IA-NE-SD? ▼
The 90th percentile AQI for the Sioux City, IA-NE-SD metro area is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 122 (USG).
How does Sioux City, IA-NE-SD compare to other metro areas? ▼
The Sioux City, IA-NE-SD metro has 80.8% good air days. Similar metros: Beaver Dam, WI (76.4% good), Bennington, VT (82.9% good), Billings, MT (86.7% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2025. See our methodology for how AQI, median, and coverage figures are computed.

Read our methodology , how this data is sourced, computed, and verified.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary files (metro-level) · 2020–2025

Every figure on PlainAir is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.